I was advanced user for quite some time and just donated to up it to premium - thought I'd have more slots to trade stuff. I deal mostly with csgo items and the space was really limited. Couldn't find any more info about this on the site, so I though it's going to scale accordingly: tf2/csgo 50/30 -> 150/120, nope, still 30 csgo slots but another 100 useless for me tf2 ones.
Is there any way to change this?

get backpack expanders, send them to your account, goto vip area of forums ask joto to use your expanders. viola... you should have another 100 slots for each expander you use.(i think)

@Joto
Thanks for looking into this, that'd be awesome. I have no real use for 1000+ slots so vip is out of the question, but some added bunch would help a lot.