Hi fellow noob!
I'm a bit confused. You're not too concerned about the $200. Jazz copy, and you want to replace it with a super-cheapo, then mod it with more $$$? Sounds like buying a rust-bucket car, and buying a new engine for it.
I think you'd be happier if you saved yer bucks to buy a "good" bass from the start. Keep in mind, the quality of the wood, the fit and finish, the hardware, all make up the final package. If you bolt on parts over cheap wood (likely to warp or crack faster than higher quality woods), it's not going to last long or perform well for the cash you've invested in it.
Buy good quality from the start, and it will last you for years. You get what you pay for. You'll also be a better player, since you'll be confident in it's ability to hold a tune, and play true to what you ask from it!
If you really want to piece together from parts, at least start with a known-good parts source. MightyMite.com had Fender licensed parts of good quality for good prices. They've been around for many years, and most of their necks are made from northern Michigan rock maple. Same stuff my '76 Precision was made from (for a lot more bucks).
I'm thinking of building one myself!
Anyway, be careful my friend. don't buy a clunker and hope to make it a BMW. It ain't gonna happen...
Shop hard for your best deal, and post what you finally decide to get!
(Classifieds here might be the perfect place to start...)
