custom amount due

Hi, I have set up a product and group for misc services and what i want to use it for is to allow customers to make payments for services based on a written agreement we have signed off on.

So i have the group and product set up. My question is how do i set it up so that they can enter an amount to pay (i dont want a default amount). They would put in the amount they want to pay as per our agreement and then they finish the order.

Any ideas, all i see in pricing is free and a default amount that i set, i dont see an option to let them put in the amount they want.

I guess i could set up three dif products, one for different donominations per month, one for $20 month, one for $50 month, one for $100 per month. But that limits me on working with customers in these hard times.

I even thought about a custom field with drop down amounts, but how to pass that amount selected to the value processed in the order i dont know the var names and such.

Any ideas would be great thanks.

Thanks

I set up the three products, service payment 20, service payment 50, and service payment 100 this will allow them to make a 20, 50 or 100 dollar pament one time.

so my next step is to set up the initial sale amount. I have my services listed, they dont have to select one of those they can just use the service payment and pay me and they get the service (honor code). But for those that want a written audit trail via email and an official order stating they ordered a particular service then yes they would select the service they want from the order form.

So lets say they select a service that is $100.00 and lets say we agreed that they would pay $20.00 per month for this service. When they do the order for the service it is going to change them $100.00 unless i do a set up coupons in different amounts.

So lets say i set up a coupon code called finance80 which gives them 80% discount and states on the coupon that they are to pay the 80% over time agreed on. So now the order form has $20.00.

This process will work as long as i can keep up with who owes me what. And also as long as i have a structured and limited choices for amounts and coupons. Otherwise this would be a nightmare if anything other than a few selections or options.

Any better ideas are appreciated. Thanks

And then i guess after i figure out how much they are going to finance, i would add a new billable item and track what they owe from there.

Not sure if i am on the right process track here.