Depends on the template - Singer ones EXCEPT for the eyelet, are not hard to come by. There are five that come with the unit, another set of four, and the eyelet.
If you do a search and look at "sold" you'll get a quick idea of what they sell for.
Now, if you are looking for something other than the older Singer/Greist set, I don't pay a lot of attention to them.
There's not much you can't get a good feel for by searching sold items on eBay. Once in a while I've not had a clue about something, and in those cases I've PM'd someone I felt might know - like SteveH on really old stuff, or Jon on Davis stuff. But mostly I decide if it's a price I'm happy with - and then I don't beat myself up if I find later I could have saved $5 by looking around more.
And it's it interesting that we will whine about paying $15 for an item that we could have got for $10, but not think anything of paying $215 for an item that we could have got for $210. It's the SAME $5! It's one thing if it's a recurring purchase, but if it's something you are only going to buy once, then saving $5 is the same either way.