"Quiero comprar unos zapatos grises."
Translation:I want to buy some gray shoes.
We live and learn. I didn’t know you could spell grey with an a! DL accepts both now.
The implication of both unos and some in this context is that you are buying a pair of shoes. 'A few' doesn't imply the same.
"I want to buy grey shoes" is the better answer, you can't always translate unos to English, it is a plural indefinite article, something that English doesn't have.