Hi Ian,
H380 is the classic powder for .22-250 but I suspect REACH means supplies will become limited now. I've had excellent results with RL15 and N140 using both 50gn and 55gn bullets in my Ruger M77 stainless but as I'm not sure there is any point to a .22-250 unless you're pushing the bullet as fast as possible, my go-to powder is now Vihtavouri N540.
Given your love of a bargain you might also try Lovex 73.6 (formerly Accurate 2520) or the newer Lovex S065 as they're both less expensive than other brands. I've found them excellent for getting decent velocity but I think they're slightly dirtier in use.
Adam.