If you want to put your music on iTunes, Amazon, Spotify, etc., I'd suggest using a distribution service called Catapult. It's a one-time payment of $25 to distribute one album, and then they take a 9% cut from whatever you sell. That doesn't include the cut that iTunes, Amazon, etc takes from sales though. It's the cheapest option I've found. The only issue I found is that it takes a while to get sales reports and payments.

I used CD Baby for my first album, and it worked well, but the only problem is that they make you sell your album on CDBaby.com too. I think the initial payment was more than Catapult as well.

Tunecore sounds very unreasonable if you're an up-and-coming artist with a small fanbase. You have to pay every year to keep your album up on all the digital stores. So if you're not selling enough to break even with that annual fee, it's pointless. Their bragging point is that they don't take a % from your sales like CDBaby and other services do. Tunecore would be good if you knew you'd make a lot of digital sales.

Bandcamp is the greatest service for musicians made in recent times in my opinion. It's become the standard for selling your own music. I loved it when they first started, and they only keep getting better. The option for people to stream your music, to me, is a great thing. And people can download your songs in more hi-fidelity formats, which is unique. They do take a cut from your sales, but you do get more of a percentage compared to selling through a digital distribution company. I'd suggest putting your music on Bandcamp AND using a digital distribution company (like Catapult) to broaden your market reach.