I'm in a panic here, anyone know a source for replacement springdown cushions that actually sells to retail customers?

I have a 12 year old sofa with hand tied springs that I had retied earlier this year. I have severe chronic pain and this is the only thing I can sit on all day without pain, yet it has felt uneven, like one side of the cushion is higher than the other when I sit. (I can only sit on the right side because the room situation-- we share housing right now and I live in a 12x12 room.) The fix helped immensely for 6 months, now I'm back to the same situation again. The people who fixed it just had a baby and are out of commission, no one else in Syracuse NY seems to be doing this work-- the other upholsterer in the city is retiring. I don't know if the problem is the sofa or the cushion, so I thought I'd get a new cushion. Only every site that seems to offer this service only sells to trade professionals, and I need this fixed ASAP. I'm in so much pain right now, I don't know what to do about this.