I'm trying to get the achievement for having 100,000 gold and right now I'm at about 53,000. I was thinking about downloading Dawnguard but I was wondering if you get tons of gold in the dlc?

Never understood the desire to chase achievements, personally.

But that particular one is an easy one to get, my current character has about 300k, and the one before that topped a million in vanilla. I don't think there are any particular money-spinners in Dawnguard, get it if you want to do the quests and enjoy the story (and the side-quest Lost to the Ages is IMO one of the best quests ever to appear in a BGS game), but IMO if it's come down to people buying games or DLC where their only interest is in getting an achievement, then that is a sorry state of affairs for the future of gaming.

Best way to make money is either to make potions, or enchant basic armor from loot, and sell the products that you make.

To get that achievement i leveled my speech-craft level to 100 and then choose perk to invest on shops. I invested in the riverwood trader and he had 20,000 gold... I just started selling random things to him and got the achievement easily.

Or you can do the Door to Oblivion Book Glitch....

Dwemer Ruins are a great way to get that Achievement because you'll get so much loot from the ruins.

OR collect almost every single Dragon Bone or Scale in the game and just keep selling them because lol they are expensive and very easy to sell

Pretty much after that achievement you're gonna end up like "...now what do with it..." wishing for money sinks.

I have enough gold to gild Proudspire manor's interior and exterior and still have some left over...

Alright thanks guys, I'm at about 58,000 now, just gonna have to keep playing to get there

To answer your question, yes Dawnguard is an excellent way to rack up on loot.

I made easy 25k just off of money and jewels not to mention the tons of gold in other things I sold. I made easily 50k. And that's just a low end guess.

Gold is easy to come by if your a thief guild member for the fences. With 3k each, it makes selling off high end gear easier. If I want money all I do is enchant a bunch of weapons with banish and sell them off for a tidy profit at the fences.

Prowlers Profit...You could get over encumbered from finding gems alone.

Excellent.

I did download it, I'm at Lord Harkin's castle right now.