I found an ad on Hoobly classifieds for a couple sugar glider joeys. Seeing as they're very young joeys I'm guessing this person is a breeder, and they seem to be knowledgeable (it says gliders are on the TPG diet and are in the TPG database). However I've heard that getting from a breeder on sites like this is a bad idea. Does this seem like a safe purchase? I've never owned gliders before so I may not be equipped to provide proper care if it turns out they have some hidden health issues.

www.hoobly.com/p/Ry6zw

I'm basically choosing between spending 500 on these or 1400 to ship two in from TPG. I have enough money for the TPG ones but hard to overlook two that are one third the price.

Hello, to me, it seems legit, the seller takes great care to precise that it's the price "pet only", which means that if you want the complete lineage (for breeding purpose) you would have to pay a breeding rights fee, which is relatively standart practice among breeders.
You can always contact the seller and ask more informations, which would allow you to make an opinion on the person, if the answers are evasive, just don't buy ;)

I have never paid more then 200 for a glider and that was my first 2.
after that it was 100 or less, many free.
if you feel you may not be equipped to provide proper care if they have health
issues. there are many options online for low cost/free rescues and rehomes.

gliders have delicate systems and can fall to illness quickly at times,they are also good at hiding illness as the weak are easiest to fall pray so they hide their weakness. they can also live 15 years.