I have 50K in Gold and want to buy my way up to 90 Pickpocketing. How much does it cost to get a skill from 20-90, without the exploit of stealing the money back?

a lot more than 50K I think after level 50 the price goes up to a few thousand

More than 50K. From UESP.net:


The cost for having a skill trained can be calculated in advance using the following formulas:
For advancement of skills smaller than or equal to 50:
n(10b + 5n + 45)
For advancement of skills greater than 50:
n(30b + 15n + 35)
For advancement of skills greater than 75:
n(50b + 25n + 25)
Where n is the number of times you wish to train and b is the current level of the skill. E.g.: If you wish to train a particular skill from level 20 to 50 (b = 20 and n = 50-20 = 30) the combined cost (250+260+270+...+540) would be 30(10*20 + 5*30 + 45) = 11850.

In short: it's faster to actually pick pocket and increase it that way.

I tried using that formula and it gave me 118K ...
Disappoint now.

Remember that you also need to level up during the trainign process as you can only buy 5 skill levels per character level. This means you need to level up 14 times for a skill to train from 20 to 90.

For the most part your pickpocketing will level enough during training process that you can burn straight through to 90 without any independent levelling.

Do you not realise how stupidly fast pickpocket levels? I naturally level it through my game, it is the fastest levelling skill IMO.

Spend that money on enchanted gear, steal [censored] loads of stuff with the thief stone active, you will be level 100 very fast.