First let me say that after having had the opportunity to work with the MarketPress plugin that it creates a clean cart that is simple to setup, style, use and operate. However, I the plug-in is missing some important features. If I am missing something or if these are on the table for near release or if there are work-arounds please let me know:
1. Item options - It seems to be lacking an Item options dropdown. Even Paypal buy now buttons, let you specify options with different prices, ie, red $2.00, green $1.75. This is pretty necessary.
2. Shipping - there is only one flat shipping rate per order across the US. This is very limiting. Even the Paypal cart lets you put in flat rates per state. Also, the job I'm working on right now requires me to give free shipping when an order total hits a certain level.
3. Sales Tax - many merchants have to charge sales tax in more than one state, again a matrix with values for each state would be best.
4. Export orders to Excel