For pricing, what I take into account is to think of it as a job. You have a few things to consider.
A job comes with an hourly rate, which in many jobs does not include a few things. So, say you wanted to get paid 8-10 dollars an hour as a novice. (5-8 for novice, 8-12 intermediate, 13-20+ for experienced? I dunno)
You then add:
materials - yarn, hooks, safety eyes, etc. Charge per skein rounded up. (If you used two skeins of A and 1.3 skeins of B, charge for 4 skeins) Your hooks and safety eyes probably weren’t expensive individually, so add like, 50c to 1$ ish
Here it looks like you used less than a skein of at least 2 colors, and the fluffy yarn tends to sit around 10/skein… ish. So, add 20$
overhead - costs like gas, paying for your spot at the market, etc. This gets broken up per plushie you expect to sell. You want to make 500, so… I dunno, let’s go 5/plushie?
10/hour + 20 for materials + 5 overhead = 35.
(Technically my math is wrong here since you said an hour and a half, so would be 20 + 21 + 5 = 46, but I’m bad at math, use your own. ^-^)
You’ve also done market research; friends, family, acquaintances, all said they would pay 35 for the turtle. That’s not them saying how much you should charge, that’s them saying it’s how much they would pay.
So 35 looks reasonable. Ish. Some numbers may vary.