Let me guess, they charged you 5% of the total order just to use PayPal? I hate it when retailers do that, it's such a crock.
How much did it work out to be per person including postage? Doesn't seem like you would have saved a lot of money for the group buy.
Who chipped in for the spare cart, everyone or just you? If everyone, doesn't that mean you pretty much got it for free, which should offset the hidden surcharge?