how much should i be expecting to pay second hand for these and what ones are good? what should i be looking out for? would a second hand baby store be cheaper than eBay or oztion?

idea? would like easy to fold, down side by side, i have a valco i think it is 3 wheeler with toddler seat but this doenst work for our lifestyle so need a side by side. This one i will be selling or swaping or getting rid of in some kinda way.

oh yeah needs to go from newborn up and be thin when folded. thanks in advance.