John's unique guitar sound is almost impossible to duplicate exactly. First of all, his 1967 Rickenbacker 325 was heavily modified and had a Gibson PAF bridge pickup and a Bigsby whammy bar. Combine that with a '68 Kustom K-200-A4 amp and you get the Suzie Q/Born On The Bayou sound...
That said, PAF pickups and those particular Kustom amps have been out of production for decades! The only Rickenbacker 325 in production today is the John Lennon model, which costs about $3000... You can always search for a vintage one or a Model 1996 reissue, but there's a small chance you'll find one under $2000... I saw a '67 325 with Bigsby on eBay the other day (of course the guitar of my dreams!) but it wouldn't go under $6000!!!
Good news is, there are many Rics which have those 'toaster' pickups and they have the right sound. John's Rickenbacker of choice nowadays is a Model 1997 with three pickups and a Bigsby. You can hear it through his old Kustom in the Premonition live version of Suzie Q and I Put A Spell On You and it sounds perfect.
I have a beat-up Model 1997 (twin-pickup and a Ric whammy bar) reissue myself and it sounds great for Creedence!
Vintage Kustom amps on the other hand are really cheap! Search on eBay and you'll find '69 models for maybe 300 bucks! BUT... it's really diifficult to find one that has the exact same distortion effects John's had.
Like Charlie said, John used Fender Concert and Vibrolux amps in the Cosmo's Factory days. I don't have much information on those, 'cause I'm a Kustom expert! LOL
Oh yeah... Gibson Les Paul Customs which are identical to John's are really easy to find. Every serious guitar shop has got one...
There is an excellent website describing CCR's (and John's, from his solo career) gear:
http://www.backonstage.halmstad.net/tk/fogindex.htm
One last thing, Stu's Kustom amp which is identical to John's is for sale. I contacted the dealer, who is a friend of Stu's, and they're asking $10,000... The amp has been used throughout the complete CCR days, so it is visible and audible at Woodstock, the Royal Albert Hall, the Oakland concert (and it's front cover) and every other of their concert footage!!!
His Fender bass has been sold but there are lots of other very cool basses up for sale! Check it out!
http://rockstarsguitars.com/product....=225&x=0&y=135
Phew... this was my biggest post ever and I've told you everything I know! Hope it helped!