If it's an automatic and it just flat out stopped, no reverse, no
low, nothing...  a transmission specialist shop is going to have to
check it out.

 If it drives at all, /gently/ drive it over and have them look - but
call first for an idea on prices and let them know you are coming.
Sometimes you can do more damage limping it to the shop in first gear,
but if it's going to need a full rebuild anyway you saved the cost of
a tow.  Six of one, half a dozen of the other.

 If they don't have to take things apart the estimates are usually
free, if they have to open the pan to take a closer look they will
want to charge a bit for a pan gasket and a few quarts of fluid.

 As for cost:  If the rest of the car is sound and strong, it's the
right size for you, and you will be able to drive the car for 5 more
years to get the value out of the repair work, a new transmission is a
lot cheaper than a new car.  Especially when you figure you'll take a
beating selling a non-running car, not much over scrap value.
 
 On the other hand...  If it's already a rust-bucket with bad brakes
and tires, cracked windshield, shredded interior, one door that
doesn't latch right and a tired engine, you might not want to sink
money into it.  Look into government emissions buy-backs, you might
get more money from them than from the wrecking yard.

 --<< Bruce >>--

Your bank account balance?'

Kevin is right, though. Check the CV Joints.