Just around the corner from hello hello (back up hill turn left at
KFC and go about 600mts) theres a 'garden center' which is really a
blokes home hobby plant place but everything $3.00

Chris & Maree's Plant Farm (www.hellohello.com.au) in Carrum Downs has
pretty good prices and a reasonable range.
Gardenworld on Springvale Road (I think it's in Dingley) usually has a
better range, although they charge a little more.