I've upgraded/replaced the entire cooling system in my '98 M3. If anyone is looking for a VERY cheap fix for a cooling system problem, here's your chance. All parts are in great working condition.

Genuine BMW water pump w/ metal impeller: $20 SOLD
Thermostat: $10 SOLD
Thermostat housing (composite): $10
Coolant expansion tank: $15
Coolant level sensor (almost new): $15 SOLD
Coolant level sensor (came with car, looks fine): $10
Upper radiator hose: $10
Lower radiator hose: $10
Auxiliary (electric) fan switch (96+ models): $8

All are light parts, so shipping shouldn't be more than $5 to anywhere in Continental US. If you buy multiple parts, I'll make you a deal :devillook

Most parts are still available. PM me for more info.