Cheaper but decent seat cushions

I currently have a 16x16 synergy solutions get seat but I absolutely hate it. It would maybe be ok if it fit properly but it's definitely too small. It came with my second hand folding quickie wheelchair but now I have a pride go chair med and need an extra seat cushion and possibly a back cushion for it because I need to sit up a little taller for it to be comfy with my legs and it's already adjusted to max chair height.

The synergy seat fixes the leg length issue but it's too narrow on my bum and hurts my hips. However the back rest part is then a little too short and not great but still better than nothing. The seat is either 18x17 or 18x18 (ice read both at different places) so I'm looking for an off the shelf thing that would fit.

I've heard good things about purple cushions but the big comfy looking one that i want the most is massive and will definitely not fit the seat. Should I get a new cushion that's actually made for wheelchairs? Or should I just stick n with trying to get some generic thing?

For reference I'm 5' 10" and about 230# any recommendations are appreciated for seat cushion and /or back rest extention or cushions. Stock photo of current cushion. Thanks!

I currently have a 16x16 synergy solutions get seat but I absolutely hate it. It would maybe be ok if it fit properly but it's definitely too small. It came with my second hand folding quickie wheelchair but now I have a pride go chair med and need an extra seat cushion and possibly a back cushion for it because I need to sit up a little taller for it to be comfy with my legs and it's already adjusted to max chair height.

The synergy seat fixes the leg length issue but it's too narrow on my bum and hurts my hips. However the back rest part is then a little too short and not great but still better than nothing. The seat is either 18x17 or 18x18 (ice read both at different places) so I'm looking for an off the shelf thing that would fit.

I've heard good things about purple cushions but the big comfy looking one that i want the most is massive and will definitely not fit the seat. Should I get a new cushion that's actually made for wheelchairs? Or should I just stick n with trying to get some generic thing?

For reference I'm 5' 10" and about 230# any recommendations are appreciated for seat cushion and /or back rest extention or cushions. Stock photo of current cushion. Thanks!