Product Tech Support

I need the occasional product support help. Customers that purchase our upcoming wordpress shopping cart script will need help with an occasional installation mishap (through our forum or by email). I am interested in being charged a flat fee per forum post or email that you answer rather than as a per hour position since it is much easier for me that way. Please bid according to how much you're interested in charging to offer support for basic email/forum help. For instance, please bid how much you would like to be paid to answer 5 emails or forum posts at a time. If support goes beyond basic needs, please note that I'll be happy to compensate for that too, but for now I need to get an idea of how much basic support will cost. Thank you!