Here's one:
1-gallon growler
The growler costs $4.50, a 2L flask costs $21.99.
Of course you'll still have to pay for shipping but if you combine it with other beer making supplies it's worth it.
You can't boil water in the growler like you can with a flask but I prefer to make my starters using a regular pot on the stove anyways. I then cool the wort in an ice-bath in the sink before transferring it to the growler.
These glass jugs give you a lot more headspace also... this helps prevent overflows caused from strong fermentations/krausen.