55 tank is a $1/gallon on sale new, unblemished and warrantied against leaks. Used wooden stand anywhere from free to $20 unless it's something special. Light/lids all depends on what kind - single dual T-8s with matching plastic lids around $30 used, glass tops and a compact fluorescent or T5 fixture, figure twice that+.
Personally I wouldn't give more than $100 for the whole shebang since they go for that or less all the time but age, quality and condition bear consideration. I'd recommend going for a 75 or even a 90 - all you're adding is 6" in depth to the footprint but what a difference that is...saw a 90 for $40 (just the tank) on Craig's this morning.
The thing about Craig's is that of you're patient and vigilant and quick you can/will get a great deal. I always include a phone number to show that you're serious and so you can maybe ask questions before making the trip.