Setting up GC so Customer determines value

Rather than offering Gift Certificates in incremental amounts, using attributes, is there a way to set them up so that the customer can enter a specific value? In other words, they go to the "Gift Certificate" product page, and the cart provides them with an option to enter a value, which would then generate a single line item in the cart. Let's say they want to buy a GC valued at $37.00. It's unlikely that I'm going to provide a series of attributes which would include that particular value.

Thanks, in advance for any help you can provide.

Make the Gift Certificate price one dollar. Then the customer can enter how many he/she wants. $1 x 37 = $37.

DrByte:

Make the Gift Certificate price one dollar. Then the customer can enter how many he/she wants. $1 x 37 = $37.

I thought about that, but doesn't the system interpret that as 37 Gift Certificates, each valued at $1.00? (Or am I missing something?)

Yes, you could look at it as being 37 items ... but since Gift Certificates are treated according to 'value' and not 'quantity', it's a moot point.
The gift certificate balance ending up in the customer's account is a value. There are no 'hard' products associated with gift certificates as far as Zen Cart is concerned.