Crustycoot makes an excellent point to take notice of! You might want to consult with a reputable high-end shop that knows a thing or two about TTs, have them do a tune-up of that TT, make sure it is well-lubricated and have them install the new cart. Installing TT carts correctly is not a job for rookies.
The fidelity performance of a cart has a lot to do with the phono stage you're using with it. Not being familiar with your TT and not knowing what your other components are, the only feedback I can offer is based on around 2.5 hours of critical listening seat-time with an Ortofon 2M Blue that I thought was very, very nice for its price. However, it was mounted on a Rega P3 and the other playmates were a Mcintosh MA 5200, Focal Aria 926 and, later, a Luxman integrated. The phono stages were the ones in the integrated amps. The vinyl used was 180g virgin vinyl well recorded albums (i.e. expensive). The Blue would be in your budget range. However, if you want to stretch that a bit, you might want to consider stepping up to the Bronze 2M provided, of course, that either of these is appropriate for your TT.
Good Luck!