First of all u might get stopped at the customs anyways even with "only" 2 sealed iphones u might face some problems. Second of all, it was mentioned before the steep ebay + paypal fees if u r using ebay. Your calculation is also missing some items. First of all, your iphone will run for $199+tax= 232 + 350 ETF = 582 + whatever charges u r going to incur for your sprint plan (i.e. they will not give you 14 days for free. U will create a line for each of thise phones and will have to incur the additional line fee as well as the mandatory internet... Bottom line, IMHO not worth it, also, i dont think u will have time to breakeven before u ll have to pay your CC.
Anyways, for the US, I think it is a dead deal. For Israel, it is a good deal when u have 1-2 to sell but for that quantity, I think u r not calculating the risks accurately enough...