I myself am dropshipping in the clothing niche. I would usually price them at 2x-2.3x of the price you got them for.
Reason being is due to discount codes which I offer up to 30%,
For mens wear, we can never find cheap clothings in retail shops.
For hoodies, I personally sell them in the $20-30 range as that is much more cheaper than my local h&m stores.
It also depends on designs(or even branding) which can make you scale up a little higher.
I sell as an affiliate (you sell other’s brand designs), this is my first time having my own brand of clothing, so I have never priced my own shirts before.
If people were buying them at that price point, that would be a great place to start.
Keep in mind that 99% of the people who buy these shirts would have no idea that it is an affiliate link / someone is getting a commission, nor to they care.