Personally, I would be just a bit more excited to participate with a small prize. Anything really counts (bonus points if its something related to F#) and could even be something more "symbolic" than "material" (e.g. getting the winning game featured in some F# community page).
Just note that doing prizes in game jams that are not widely known is kinda tricky because there's so little people to begin with. On one hand, it would help push some people towards participating (makes you feel like it is more worth your time and effort). However, if coming up with a prize involves asking for a participation fee, a bunch of other folks are immediately discouraged.