I don't make my own these days, but it is easily done. Salicylic acid is available and the online sellers seams to be the best on price. It can be a bit cumbersome to measure the exact % and streangth the first times and the right equipment is necessary. The skinactive people (skinactive.com) call it willow extract (as the salicylic acid is naturally produced by the willow tree).
Right now I use one from a seller on ebay.uk. I feel I get the most for my money here. I use mostly the lactic / salicylic peel, but the 20% peel too (this is the strongest, don't be afraid to try the milder ones 10%, 15%. Your skin should look fine, feel soft and comfortable the rest of the week. Though you will feel the action of the peel for 30 minutes or so after. They sting more than you would like the first times, especially the lactic, but use a nutralizer when the peel have worked for a minute or so, and the stinging is over in 8 seconds. You can let the peels work longer after the first few peels, but only one minute increase every/every other time. I think 7 min. is maximum recomended time for home use. Nutralizer is baking soda dissolved in a bit if water and perhaps some aloe gel or other skin soothing agents. Let this work for a minute or so. Salicylic is the mildest and very safe for longterm use, but not for those with dry skin. It is the salicyIic acid that dissolves hardened sebum and helps it come to the surface naturally. I have mostly used the serum and the peels and not the other products from the UK seller because I'm alergic to hazelnuts and this beautician really likes this oil in her creams.
There are many similar products available in stores and on the net. Though the serious peels are not allways that easy to find. I really like the products from the Skinactive site, but from US the postage can be rather expensive so I order only a few now and then. They have a T-sone serum and a peel kit that is worth checking out.
These two websites are the ones that I use, but as I have mentioned repeatedly there are several out there. If you try the peels you can all ways use it together with your usual products and take it from there.
I don't recomend the benzo peroxide used in many products, it works fast and kills bacteria but is not that good for your skin longterm. These conditions most often last for years and the skin care too.
I was not allowed to post URLs as I am too newly registered here. But the ebay.uk shop is called "forever young" and if you search for "salicylic acid" several products turn up. The US site is called skinactives.com
Good luck with your skin care search !