Maybe start with a cheap one from ebay or AliExpress. You can pick up a Tauwell one for less than £10. Look out for the sizes though, they tend to be labeled up in Asian sizes, so go at least one size up from your normal clothes.
Alternatively, wait for one of Aussiebum's 50% off sales (they tend to have them practically every month!) and pick up one of those.
If you've decided to already go in with a decent quality one, then Bumchumbs are a small UK company and their singlets are very nice, they are a fuller cut on the top, so not as "skimpy" which suits those of us who don't have gym titties.
Love you, too
