It depends on who you talk to...

I think it "makes senses" either way, but I rule it as a level 4 cost 400. I think the majority of GMs rule it that way, but if you want to give up a level 4 program at 250, go for it. It doesn't matter what "we" think, it matters what the GM and players think in your group...

It's been said before, but unless you want your players saving their money for long stretches of time to make big upgrades, just let them pay the difference.
I prefer to see lots of incremental upgrades, so I make it as easy as possible to take that approach.

Uh yes, that is pretty much the definition of not making sense. Everything has an escalating cost based on value. The Value diference between 3 and a 4 is no greater than a 2 and a 3, so why is the price so much more?

not exactly. You roll more dice with a higher program rating. I don't think the probability of success with more dice is linear, but then I'm not mathematician.

Well there are diminishing returns for investment. You could make the same argument about attributes(why the final point costs 25 BP in comparison to all the other points costing 10) the final point isn't a linear progression. Look at hardware upgrades they don't look to be linear. Improving things with karma acts this way, each stat costs progressively more while only giving a single additional die.

Also from a non game mechanics point of view it makes sense that once you start buying the better equipment they'll have a higher mark up. If the people need the best equipment in general people are going to charge more for the best equipment.

I think the thing you are leaving out is the "to you". Its not that it doesn't make sense, its that it doesn't make sense, to you.

I agree, that the difference between 2 and 3 is no greater than 3 and 4, but with a 6 point rating system and what the rules seem to be implying, is that up to rating 3, there is a lot more availability, whereas getting to 4, 5 and 6 are a lot more restrictive and rare.

For example, in my game, for purposes of training, I allow my players to find instruction programs up to rating 3 on the matrix, but anything above that, they need an "in the flesh" instructor. Skills, attributes and device ratings, all seem to have a break between 3 and 4...so to me, having this non-linear increase between 3 and 4, well, makes sense to me and my game.

As to the "upgrade". Whether it makes sense or not, I simply charge the full cost for a program rating 4, even if "upgrading" from rating 3. Again, its just a matter of balance in your particular game. Our group usually has enough nuyen as to not make this a big deal...so, as long as my players are aware of how I run, everything is cool.

Actually, I'd ask more why rating 3 or less is soooo much cheaper.

Have you ever noticed the difference between personal video editing software and professional video editing software? The personal stuff ranges from about US$30 to about US$120. The professional stuff ranges from about US$500 to US$3,000.

That's why there's a gap.