Hey, i'm a longtime customer of MTGOtraders. I would singlehandedly make 90% of my MTG card (digital and non) business yours, if you had the option to create decks and sold them like many other card stores do.. (off the top of my head, "anothermagicseller") does this.. (and i currently use them for all of my paper business because they have that feature and a 10% discount for full decks bought)
If you were to implement this function heath, you would gain a customer for paper, as well as having an already lifelong customer for digital cards.
The 10% discount on built decks isn't necessary, but it'd be nice to have along with the option to build decks (you can use the same software you use for MTGOtraders, although you might alienate those without it to build decks and buy them (which is bad) i suggest. itemized card lists for decks (like people do on MTGS and the WotC boards.) can be uploaded directly into a form, which then prices each single card and tallies the overall price (like starcitygames has)
Thanks for your time heath... and i look forward to you implementing a pre-built deck idea...
*removed website name. Hope you don't mind.