Yes it is a VERY viable route to start an online store. That is how I ran my entire store before I sold it (www.pbparadise.com). I set up the oscommerce, skinned it, coded a lot of the plugins and contributions, and made it all automated. To the point where it would work like this:
1) Client buys product
2) System recognizes the product purchased
3) Accepts credit card payment
4) System checks 4-5 suppliers I had connected to via the backend
5) "Sees" what supplier has the product in stock
6) Dispatch email to client confirming order, to supplier with DROPSHIP address, and to me letting me know order was made.
7) 3 days later client gets paintball gun with my packaging/promo goodies, and he never knew it came from Texas and I was in NC.
ONLY ADVICE I CAN GIVE YOU IS MAKE SURE THE SUPPLIERS ARE REPUTABLE!!!
Check references, order a few times and dropship to friends/family, call them up and see how responsive they are.