Extra fields for existing form

I need to add 500 checkboxes to my existing user registration form. Dont worry about labeling the checkboxes,I will painstakingly do that. I need the information from the boxes put into a database into the following categories. 1)All the boxes that are check should go into the want table. 2)All the boxes that were NOT checked should go into the dont want table. The tables must be linked to the user who originally filled out the form so other users will be able to contact them. I want the want table ONLY to display the information from the want table, and I only want the search to return matches from the dont want table. I want to give the original user the ability to edit their post and hide boxes from either the want or dont want tables. Depending on the complexity I also need the non poster to be able to check the checkboxes and contact the original poster.(which would take the text value from the checkbox and email the poster) I would also need the ability to add or take away checkboxes(not many each time) Maybe I could add the html code for the extra boxes when I need them. I am running a classifieds site here so the form im requesting just needs to be incorporated into my site. [login to view URL] Post an ad and you will be able to see what my current form looks like. The fine print. I dont have a lot of money to throw around,so I am offering as payment the following piece of hardware(new in box) Its worth approx $700 You will pay for shipping and it should be around $75 anywhere in north america.