Would probably cost you like 75-100m in chins.
Cheaper and less attentive to simply NMZ&Blowpipe it.
I'd be quite happy to take this on for 50m (the blowpipe method) and leave you a few dozen exp from 99 just so you can finish it yourself. xxxx
Username login (created by me 9 years ago)
Used only by me and NEVER botted.
99 Slay
Quest cape
All hard achievement diaries (some elite)
Elite void (3 helms)
3 pets
20 day cooling period is absolutely ridiculous when there's a very small, but very real chance of the accounts being banned within 12 hours of you starting to bot on them.
Fucking love Slayer.
99'd twice.
Assuming you will be funding the account with necessary gear and supplies, I'll do:
Acc #1 for 25m
Acc #2 for 26m
(Edit reason: knocked 5m off each price after recalculating)