Yea, you don't need a POS system. If your looking at just doing on the fly costing a decent spread sheet will work. If you need a more indepth look at your inventory I would say use the iPad to VPN and remote into a pc that is running your accounting software.
I also would not advise to runing and storing your accounting/inventory data from a iPad either. They have a way of getting broke or growing legs if one is not careful.
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