We have some from K-Mart. They came in a 3-pack (blue, pink & purple) and they look good enough that Nat often requests to take her top off and just wear her singlet, lol. I found some bonds ones with adjustable straps (size 6-8) in the Salvos store the other day! $1.50 each! With tags still on.
I like singlets here as Nat particularly isn't big on jumpers so I like to add the extra layer in winter.