Is it a waste to have a saddle if you just take lessons?

I just take lessons now but I want to save up for a horse item... I only have a mini horse and I'm hoping to care for another horse soon but I don't think I'd be using the saddle on them, at least not the mini... what do you think? even with OR without a convertible gullet? I'm not thinking going all-out for, like, a $2500 dressage saddle. Just thinking about a cheap used close contact in good condition if I could find out and pay for one?