You can buy standard bass necks (2 1/2" [width] x 3 7/8" pocket) from www.stewmac.com
. A Hard Rock Maple neck will run about $135, and they conform to Fender specs.
A less expensive alternative would be to get one from Rondo Music at www.rondomusic.com
. The 34" inch scale model (Maple) will run about $60 USD (some have nuts installed and some don't, so make sure you check out the description).
Make sure you measure the diameter of the tuner holes in your current neck. If they match (the Jazz Necks from Rondo have 1/2" diam. tuner holes), then you're all set.
I bought a Jazz Neck (SX Bass Neck SJB-75CT) with white blocked inlays from Rondo a few months back. Installation was as easy as swapping out the tuners from the old neck, bolting (4-bolt) on the new neck to the body and then re-stringing.
Other adjustments, such as truss rod, intonation, etc. were fairly easy to do if you follow some of the help provided in the Stickys on the Setup & Repair Forum here on TB.
Also, take my opinion lightly (I've only been playing a little over 2 years), as there are lots of people here on TB who have much more experience with other replacement parts (Warmouth, All-Parts, etc).
You can also check out eBay for bass necks.