on topic of Idlers not sure where dude went with that:
I only have 6 idlers (which is a really small amount compared to most) and I idle 2 a night for 3 nights (whenever i remember) with the free version of sandboxie (free gets you 1 sandboxxed program, paid gets you as many as you want, but 1 is more then enough). with them 6 i amassed a nice little steam library....decked out tf2 characters so in the end Im way ahead my initial 30-40 dollar investment.
alts good to store crap as well....i got a crapload of crates i really need to get rid of and have my Halloween sets (normal+haunted complete) and other assorted stuff in alts
Quick math I did on idling, note that I didn't want to factor drop percentages and what hats are worth more than others, so this is the minimum you'll get from idling.
You get 10 weapons per account per week.
Which you can easily turn into 5 scrap.
Which is 0.55 ref.
Which is 1/5 of a key.
Which isn't more than $0.28.
It's easier to just round it out to $1/month/account.
Let's say that hats/misc drop at a 1 per 100 weapons. You'll get a minimum of around 0.66 ref per account.
So you end up getting $2/month/account.
For me it wasn't worth the initial investment (was looking at 5 alt accounts).
Is my math 100% accurate? Not at all, as I said I calculated the worst case scenario. For example, I'm sure a lot of idlers made mad bank on all the Pile of Ashes they had when the Pyromania update hit, selling the weaps for 1rec+. Also I bet many alt accounts had Secret Diaries drop for them.
Right now I'm happy enough buying keys from the black market and trading them for the stuff I want.
As I said before I'm not into collecting this kind of stuff, just like to have my characters look cool, so it's not like I'm spending huge amounts of money to justify looking for "get rich" schemes.
Also, I only got into TF2 trading because of Dota 2 getting items. Otherwise I'd still be rocking default stuff with the random drop hat for all my classes.