I am currently a booster at ELO-Boost.net, and I've been boosting on the site almost daily for around a year, the average payment have been around 300-500euro for me a week, since there is always orders to climb and 60% goes to the booster.
I'd suggest you to be around d1-challenger if you wanna boost the highest paid orders, but there's bronze-challenger, non stop.
The account is well known on the site, and I've always had good relationship with the admins as well.
ELO-Boost.net is by far the hardest website to get hired as a booster, and requires challenger solo queue, or EX LCS. It is also by far the best paying website, for a good booster.
I sell the account because I'm working fulltime irl, and wants to move on from league, since I'm kinda burned out from all the gaming.
I'll provide all necessary proof for a potential buyer.
PM me, only serious offers.