Don't buy one!
If you already have an air pump, then you are 90% there equipment wise. Save that money for the BBS eggs.
Google "DIY brine shrimp hatchery" and follow creation of one using a 2L soft drink bottle.
It should include instruction on how to hatch the eggs too.
The first 2 weeks are critical. If they survive and eat BBS, then you can start introducing other foods.
Try bee pollen. I use that to feed baby shrimps in rotation with other powdered foods.
If you don't use it up, heck, it's good for humans to eat too! You can find many on ebay.
Spirulina is good too, as Simon mentioned.
In the first few weeks BBS is essential. It's not the same as Frozen BBS. The wriggling movements of newly hatched BBS attracts them to eat. You can try frozen, but you'll find them ignoring it, and the leftovers will just rot.
That's ok then, I thought you must have lost a lot or something!
The dwarf puffers are interesting but you can't even keep snails with them as they eat anything that moves? The dwarf rasboras like similar conditions to TB shrimp. I will see what happens with next weeks delivery of shrimps first and decide from there? In theory I could keep both as it is a heavily planted tank so some baby shrimp should survive - if I even get any that is? One step at a time!