How much would it usually cost to fix the transmission on a 98 nissan maxima? the reverse doesnt work =/

Automatics would usually run around $2000 r&r with a reman. Manuals are about the same. You may strike luck finding a smaller shop that specializes in transmissions and get a rebuild with warrenty for around $1500.

Throw the car away ,or trade it in on a renewal plan ,cost of repair is more than car is worth ,also parts not available from dealer only a complete exchange gearbox which with value added tax is around 3000 euros plus labour