i don't know about console commands, im on PS3. but there is a Speech glitch. Go to Riften and talk to the guy in the Black Briar meadery behind the counter (Uthergen?), and choose 'Tell me about Maven' and then keep choosing the 'Persuade' option.
You will get Speech skill to 100, and choose all the perks. This gives most vendors in Skyrim (except Innkeepers) +1000 gold to barter with. And another perk allows you to invest 500 gold in some stores. Another perk gives you 30% or 50% (forget which) discount when dealing with trader of opposite gender. Another perk allows you to buy/sell all items (eg potions to a blacksmith etc). Lastly, there is a good thing with Riverwood Trader. If you have Golden Claw in your quest journal (dont have to complete it) and then choose to invest 500 gold in the store, then he has 10,000+ gold coins for trading