Just a suggestion.
I have some wheels for sale on your site atm and would happily donate some cash towards server fees as a 'thank you' for the privilege if/when they are sold.
(I run my own free site also and realize the amount of time and cost to do so isn't cheap, though it is done for the benefit of others ).
Maybe some other grateful members would do the same?
A simple PayPal button directing users to your PP would do it.
Cheers, Sam.