I think if you are uninterested in getting the Shaymins to run Vespiquen, then I would probably suggest looking into other decks that don't require them. Example: Greninja doesn't require them and is a *somewhat* budget friendly deck. Another deck that can get away without Shaymins (but isn't as competitive without them) is a Xerneas Break deck. It is the type of deck that can stack energy quickly to fuel Xerneas Break's attack with or without Shaymin. If you are looking for something competitive that isn't running Shaymin though, Greninja is the best of that list.
Edit: I also have a friend who runs a Volcanion / Delphox Break deck that is pretty strong and quite cheap to put together. It is a slower deck and you would need to modify it to remove XY Delphox and replace it with something else (there is only one of them), but it does well. If you are interested in that, I can PM it to you.