I would really recommend Revlon Colorstay for Oily/Combination skin. It's about $11-$13 depending on where you purchase it but it is worth every penny. This foundation has now replaced my MUFE HD foundation that was $42!! The best way to find the right shade is to take in a bottle that you are already using and try to find the closest shade. Thats what I did and I was able to purchase the right shade. I will warn you though, you will need a good makeup remover with this product because it really stays on. Walgreens has a sale right now 30% off all Revlon products so you can get it at a discounted price. Good luck finding your foundation.

The Revlon mousse line is also nice. It is a bit lighter on the skin and doesn't clog pores. 

It's great that the others are recommending Revlon Color Stay, but that doesn't mean it is going to suit your skin the best. Try to get a product with some SPF in it, especially since warmer weather is here. I like Neutrogena and Physicians Formula because they have a lot of self-adjusting products with SPF. Maybelline also has a new BB (beauty balm) that is more of a tinted moisturizer, but it won't make you break out. You could use it under another product, and still get the bennies and SPF.

I used to use Too Faced, but it just seemed too runny with little coverage. I was visiting Walgreens and saw a display for Revlon Colorstay Whipped Creme Makeup. The manager of the beauty products department showed me that you can sample this product. The sample was in the lightest color, but I was able to see the consistency, coverage and application. I loved it! It had so much coverage and was not runny. Together we picked out the best color for me--natural beige, which turned out to be the perfect color. The department manager said I could return it if it didn't work out. They were having a buy one get one 1/2 off of Revlon products. Rather than commit to another foundation (in case I didn't like it), I bought an all day pencil style lipstick. I wish I had bought that that second jar. The price was $14 or $15. I usually have dry skin in winter, but with the heat we have this summer, my skin is oily. This foundation is not greasy at all. My face does not feel weighted down by this product. This is a real keeper.

Revlon colorstay is definitely good!! I keep going back to it.

I love MAC ProLongwear. It's not super cheap, but it's the only one that works on my oily and acne-prone skin.

It's already been said -- but Revlon Colorstay. I also have acne prone skin and this works so well for me. It has amazing coverage. I actually discovered this when I was looking for a foundation for my wedding day. It has amazing reviews, never made me break out, and gives beautiful coverage without caking. It does not contain much SPF, but that's why I first found it. Foundations with high SPF will actually reflect flash photography back and make you look washed out in pictures (not something I wanted on my wedding day). If you want more SPF coverage, you can always use a moisturizer with it beforehand.