Buying a Force 4 Reach 1 weapon would cost around 560 000

, times 2 if you're paying street price for it. It would cost 16 karma to bond.
Making a Force 4 Reach 1 weapon would cost 1K and 32 karma if you just enchanted a shiny new (or old, or what have you) katana, plus the cost of any exotic materials the GM decided you need (this could range from about free- a lock of hair or whatnot from an Awakened critter, which you could probably pick up on a run to the local zoo- to 60K or up). By standard rules, you've got a 4-in-6 chance of needing some sort of exotic material.
You can decrease the Karma cost, but if you're making a metal weapon, good luck on the virgin telesma- you'd need to mine and refine the metal yourself, which besides being expensive (Really, are they just going to leave an open viable mine lying around for you to dive into?) is probably a bit beyond the scope of Edged Weapon B/R. Likewise, I hope you're into herbs; since ALL the materials going into the object have to be virgin for that little -1 karma bonus, you'd have to collect and refine all of it yourself. Huge waste of time. If someone actually managed virgin telesma on a weapon in one of my games, I'd probably give him at
least -6 karma (up to as high as -12 or so, depending on how far he goes with it), but that's beside the point.
Assuming you go with handmade telesma and three radicals, you're probably looking at anywhere from materials (probably around 500

for a katana) + 440

to... well, a lot more. This'll get you -5 karma cost, for a grand total of probably around 2k

and 27 karma for your hand-made sword. The difficulty of the enchanting test will be either 10 or 8 (I'm not sure if you're allowed to start the enchanting back when you've got the raw materials or not).
Edit: Oh, and karma costs go up pretty fast when you're bonding weapon focuses. The first number is force, the first before the slash is 'premade' and the second is 'first bonding'.
5:20/40
6:24/48
7:28/56
and so on
Sigh. I'd love to have an adept with a force-7 sword, but that's just freakin' overkill, and would be the focus of a entire campaign. Sadly, I'm the GM.
Or luckily, depending on your point of view. *cackles*
You could probably expect to be spending well over a mil on a Force 8-10 weapon you enchant yourself, just in the costs of getting the radicals and exotics in order to make the thing enchantable.