from my experience now i can only advise you to not spend any money at all for your indie projects, only if its really, really nessecary!

for my current project utz wollewutz i bought some sounds and music really cheap! the rest is almost all selfdone stuff. now that i have contacted several publishers the offers they made make me laugh, they are so unrealistic. my game is finished, 99.99% bugfree, comes with manual, fansite, is multilingual, pretty unique and so on. meaning the publisher has zero!!! risk at all and zero!!! money to put in compared to other projects.
however with the contracts you get offered you even have problems getting the money you invested back. iam happy when the game is sold and i am not in the reds with the invested money for this project. and the stuff i bought was really, really, really cheap.

so for my next projects i plan on using as much open source software as possible. even improve my own art skills so i dont have to buy expensive stuff everywhere else. you basically have to be a master of sound/music, code, modelling, mapping, 2d gfx if you are an indie or you will have problems to make a living.

the next thing you have to keep in mind is that when you buy stuff everyone and their mother wants to be mentioned in the credits or say, you can use my stuff until you sold xxxx copies then i want to get more money. this is insane.

dont get me wrong, i just want to advise you not to spend money on indie projects. unless you have THAT killer idea THAT will definitaley sell its not worth it.

you probably have to pump out 1 little crap game a month and sign unfair contracts for each one to make little money that adds up in the end to make a living or you have this superdupergameidea and can finish it.

maybe some others can give their experience too. iam even thinking about not going to a publisher at all and selling the game on my own, this will probably get me more money even if i sell only 10 copies at all.

in my situation i wasted like 4 month working fulltime, if i would have stood in the city selling sausages i would have made more money - but its not only the money that makes me doing this.