In the resources tab, you'll find items to buy with ironite, gold, and money.
Sands of Time
Sands may be purchased for Ironite as either a fill of your sands meter or as 5 fills. There is no price break for buying the 5, it's simply there for convenience. There is also an option to purchase a drip pack as a 7 Day Boost, which will give you an extra fill daily for a few dollars. This is one of those items that many players find to be a good value for real world dollars.
Packs of 1, 3, or 10 rare souls may be purchased for ironite. While there's no increased value getting the 3 over the 1, purchasing the 10 pack essentially gives you 10 for the price of 9. If you need some characters early on, this is a way to start building up your roster.
1 and 3 day boosts are available for ironite. If you think you might want 2 days, pay for the 3 since it's the same price. This will allow your characters to level up twice as fast and is a good boost in your stats, especially early on when the levels you can play don't give you nearly as much XP for your higher level toons.
At 2 million gold and a limit of 2 per month, this will require some heavy duty farming if you want to keep buying them this way.
For only 10 million gold (can you feel the sarcasm?), you can grab yourself a Legendary soul. This one isn't considered by most players to be a good value.
You can buy gold for ironite or for real world dollars as well. The exchange rate isn't all that great, so we'd highly recommend finding another source of gold if you can.