Replying to HELP! where can i rent car, outerwear, shoes, skis Denver

Hi everybody.
This is a big help.

I'll be soon (2 january) at Denver and into the moutains near the city. I come from Switzerland and will be there to ski and to travel around the country.

BUT, I'll sleep at my aunt's bestfriend and I need to transporte her from DEN to her cotage.

So, I'll rent a car but do you know where can i rent a car WITHOUT underage tax? i'm 21 yrs old.

Other question, my outerwear, can I buy some very very cheap outerwear there? someone has a lot of XXL outerwear and want to sell them for cheap?

I need shoes too and skis twintip everything for cheap.

please let me know if you sell old things thanks you so much
Simon