There are a variety of things that can be 'bought' with your Karma. Remember, Karma is not money, per-se, but your ability to make the 'Verse work in your favor.
Here's a list of some of the things you can purchase, with Karma:
Skills cost Skill Points, which are bought with Karmans. Here's the cost table:
SP Costs: 1 2 3 4 5 6 7 8 9 10 ------------------------------------------- 1 3 5 7 9 11 13 15 17 20
Buying a new skill costs 1 Point. Going from Level 3 to Level 5 would cost 16 Points.
Tools, such as guns, repair kits, or even good clothes cost Karma. Generally, the higher the level, the more they will set you back. In most cases, An item's level will cost 10 Karmans. So, if you buy an L3 Weapon, it will cost 30 Karmans. However, some places may be more or less expensive. That right nice shootin' iron on a backwater moon will cost you a lot more.
Big Damn Things
Want a ship, or a shop? Perhaps a home to put your very own Vera to rest each night? Certainly! Costs vary, ships tend to be more expensive than a shuttle or a shop. However, major purchases give you things most folk don't have. A ship, for example, gives you the freedom of the Black. And that's not half bad.
Remember: You can spend past 0 Karmans, so be careful! If you go negative, make sure you're not going to be caught in a running gun battle anytime soon!