I've run some numbers, and here's the best way I can figure of doing this, pre Matrix book:

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Upgrade cost:

DR = new rating x 10000
Avail (3 x new rating)R

Attribute = new rating x 3000 (1-3)
Attribute = new rating x 5000 (4-6)
Attribute = new rating x 8000 (7+)
Avail (2 x new rating)R

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Upgrades have to be costed sequentially (from 2 to 3 then 3 to 4, etc), so the cost of upgrading an attribute from 2 to 4 would be (3x3000 + 4x5000) = 29,000.

There should probably be some minimum device rating for any particular attribute array, but for the life of me I can't figure out what that should be. Here's my best stab:

The minimum attribute in the array must be greater than or equal to the device rating. For example, if you want to upgrade an Erika MCD-1 (DR1, 4 3 2 1) to DR2, you must first raise the least value in the array to 2 (costing 20,000 for the DR upgrade, and 6,000 for the attribute upgrade).

The maximum attribute in the array cannot be more than the DR + 4.

Each individual upgrade requires a Hardware + Logic [Mental] (New Rating, 1 day) extended test to complete.

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Upgrading a commlink into a cyberdeck:

A commlink can be upgraded into a rudimentary deck by reseting its Device Rating to 1, and then distributing its former device rating into an attribute array as evenly as possible. You must also add a sim module (preferably a hot-sim module). For example, a Hermes Ikon (DR5) can be converted into the following deck: DR1 (2, 1, 1, 1).

This is done with a Hardware + Logic [Mental] (Commlink DR, 1 day) extended test, and requires (Commlink DR x 100) nuyen worth of electronics.

The commlink must be of at least DR 4 to be converted.

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Warning: In all cases the above is overall more expensive than the price gap between two decks -- that is, to upgrade the Erika MCD-1 by the one attribute point needed to make it essentially a Microdeck Summit costs 9000 nuyen, where the price difference between those two decks is only 8,500 nuyen. Only a 500 nuyen difference, but that number goes up pretty steadily. I think the most egregious entry is the Shiawase Cyber-5 to Fairlight Excalibur upgrade, which costs 20,000 more nuyen than the price difference.

It is, however, much cheaper than hocking a deck at 1/3 cost and then paying the difference for the next step up.

Regarding the commlink conversion, upgrading a Transys Avalon (5000 nuyen + 600 in parts) to Erika MCD-1 levels is 44,950 -- 49,950, or 450 nuyen more than just buying the Erika off the shelf, which I think is a pretty good fit.

The Hermes Ikon is a little rougher at (3000 + 500) and then 50,350 in upgrades -- 53,500, or 4350 nuyen more. The Erika Elite is an even worse choice monetarily. The Fairlight Caliban is the best choice, coming out slightly cheaper overall -- but those better commlinks have very high Availability, which has got to be worth something.

The truly posh can also turn their eyes to China, where certain parties claim scientists have discovered an Emerged breed of waterfowl that has consistently shown Resonance abilities in each successive generation.

While still unable to clone these, natural breeding still yields 3-8 young and with the more controlled lab conditions the survival rate is fairly high.

During their formative time, the company provide an electronic environment for the hatchlings to orientate with and learn to navigate, using their resonance abilities to hack their way through obstacles to obtain food and shelter.

During this time they are also subjected to a series of operations. (Animal activists may not wish to read the following)

First they are sterilized so as to ensure that only the Company will be able to provide viable replacements/future stock.

Then a specially redesigned CAST, referred to as CASHEW (Computer Assistance System for Handling Emerged Wildlife), is introduced into the biosystem and training adjusted to integrate the usage of the new system. Building on the CAST system it utilizes the emerged animals developed skills so while the user designates the targets and level of involvement-perhaps designating an IC program as a hostile or a particular data pack as a tasty tidbit to chase, the animal still uses largely it's own instincts to accomplish the task as all attempts for outside systems to actively initiate the animal's TM abilities remotely have shown poor results to date, the animal itself must choose to do so though the system can provide the necessary triggers to encourage the desired effect.
Buyers are brought in at this stage for training to work with the animal as well as how to operate the CASHEW system. This normally involves a period over 1-2 months. While the insertion of the CASHEW does inhibit some of their talent, the unique experience of dancing the matrix via the translated senses of an emerged animal is not to be missed. An interesting side effect is that the animal rebonds to the final user, treating the owner as it's new parent. This has the added benefit of making them more malleable to the will of the user.

By month 7 the emerged avian is fully mature and ready to be deployed.

So for a cool 2.73 million nuyen, you too can get your very own Peking CyberDuck with CASHEW and try your hand at Quacking on the Fly.

Sendaz.... Just.... *Sigh* No words at all... Never Mind... *shakes head*

Ignoring the funny duck... had to lol

Seems very reasonable house rules to me. I never liked the lack of upgradability in SR and usually houserule that you can upgrade for the difference between old and new + implantation cost, if any. But this also seem like very good rules for custom deck building, so thanks.

Cool. It's based on the cost differences of the actual decks with a couple assumptions and some hefty rounding.

I'm assuming that when the Matrix book actually comes out, there'll be fancy toys you can build into your deck and really make it unique.

Yeah, I also hope for some TM love in that book, at least. It seems like they used a formula similar to yours, but fudged the numbers a bit to make it less obvious. Kind of like retail prices.

Good piece of reverse engineering.