It might seem counter intuitive but I really recommend that you try getting some clothes made if you are looking to save money. Discount plus size clothing often doesn't last very long and I find it rarely fits well either.
For much less than you probably expect, you can get some pieces made for you by finding a tailor online, through a store like Etsy.
They'll make it to your measurements, and some of them specialize in plus sizes, so they'll know how to make you look wonderful.
I've had several things made and I've never regretted it. And I know that the clothes will last much longer than something from a discount store.