I think it'* a great idea
On two different other sites that I'm also a member off, they have an option to support the site. One is $15 and the other is a couple more dollars for the year. With that membership you get a few other forum topics for supporters only. You also get stamped SUPPORTER in your with your user name field area. That is optional to all members on those sites to help support it, but it isn't mandatoy, and those sites are free to all members. I also think that is a great idea because those that don't buy anything from the store could still help support this site and feel good about doing it.
1995 Bonneville SSE ...... L36 3800 Series II N/A V6, FE2 3.06 gears .......... 224K
2005 F150 Lariat Chrome Edition . Trition 5.4L Modular V8, 4x4 3.73ls gears .. 44K
2001 Wellcraft Martinique 2400 ....... MerCruiser 5.7L EFI Bravo III ............. 220hrs