hi Carrie,
The way you use commas in a selection value is you start the value list with a backslash (\) the value separator you want to use (;) and then another backslash (\).
So if i wanted a value list:
1,000
2,000
3,000
I would write this: \;\Select One...::Select One; 1,000::1000; 2,000::2000; 3,000::3000
The double colons (::) indicate that the value to their left will appear in the form, but the value on the right will be entered into Marketo as the value.
Hope this helps you!
Best,
Elizabeth