Mickey,
You need to invest if you are serious about business. You should have 5 to 10 styles in stock at least, and then you can present new designs in line sheets (catalogs). T-shrits are already cheap to produce and you can sell many of the same designs season after season. I make fashion garments and we don't have it as easy.
One shoulder tops might still sell now, but I might have to close out any inventory for dirty cheap next year. There are thousands of clothing brands out there with fresh designs every week and inventory ready to ship. Don't look like a complete amateur to retailers by having only a few computuer print outs to show and nothing to sell.
Some retailers can wait some can't. Hot Topic gave me 4 weeks to ship, but some boutiques wanted goods asap. It depends.
You can build your business with a small collection, but you still need to look professional, and not like a starving artist.