West Marine or any of those type of boat places that sell sailing hardware will have all kinds of pulleys, cleats, etc. that you could do it yourself. That stuff isn’t cheap either but you could probably figure something out. Pulley’s and cleats are one thing but part of your issue is going to be the mast off the back but a lopro and length of pipe solves that. You’ll want some decent rope and just a pyramid or animal anchor will cost you $90-100 so might want to think about finding some used dumbbells or plates.
I just bought the NRS system and use a Hyde animal anchor with an ez pull system I made from REI climbing parts. Sometimes it’s just nice to have the right parts that were built for that purpose. The NRS system isn’t as nice as the through the frame ones but it works well.