Always insist on refundable, don't play ball if they won't.
Called the other dealer that didn't sell out from under me to tell them I wanted the white ST I drove on Friday. They repeated the reasonable price they mentioned Friday but said something about $1k in dealer fees...which sounds like them trying to pocket the rebate. They also sent their "stock" deposit form which stated "non-refundable." I emailed back saying that if they won't take refundable, I'll take my chances and show up Friday. Got a fax with "non" marked out and an email saying "refundable is fine." So now there's a refundable deposit holding my likely future Fiesta ST. I told them we'll talk about these "dealer fees" when I arrive on Friday and after I look up whether there are limits on fees in TN. It's spot on price-wise with the going rate without their fee.
New lesson for those buying cars. Don't be afraid to push back when something doesn't sound right.