Welcome, and I do think you picked the best spot for your question.
Old Bridge's system is still all-analog, and the NJSP system is still mostly analog, so an analog trunktracker should suit you fine.
Old Bridge's trunked system will undergo a retuning because of some wide-spread technical problems (NJSP just switched, South Brunswick and Middlesex County changed a little while ago). Although it is unlikely in Old Bridge's circumstance, there is potential for some older scanners to stop working on the system when the retuning happens. For this reason I would caution you against buying older used trunktrackers at least until Old Bridge makes the change and you can be confident those older scanners will still work.
There's still a lively market for newer used scanners on the net, just make sure you get a model from the past couple years. If you see a used one that catches your eye you can post its make/model here for us to comment upon.
Of new base/mobile models, I would suggest the GRE PSR-400 or the Uniden BCT-15X.
www.ScannerMaster.com is a well-regarded online retailer (and sponsor of this site) and they're running a sale on those models for $139 and $209, respectively until Monday. For more info on that sale check out the recent post in the Community Announcements and News forum.
Whatever scanner you get, you'll want software and a programming cable for it. Some scanners come with free software, you can download free 3rd-party software online for some models, and if you can't find any free software that's any good then you can usually buy some for about $30. Make sure the scanner comes with a power supply and programming cable, or plan on buying them separately.
If you've got the budget for it then you can consider going right to a digital scanner now, but they start at $400 on sale and go up to some $500 or $525. For reference the two digital base/mobile models I'd recommend are the GRE PSR-600 and the Uniden BCD996XT.
If Radio Shack is running a sale then their prices may be better than prices on GRE and Uniden-branded models but RS units generally don't come with as many accessories (power supply, programming cable) as GRE and Uniden. GRE is the OEM for most or all RS models so differences between them will usually only be cosmetic and bundled accessories.
Good luck,
Jim