Adsense is a great tool for advertising high ticket items. It is also useful if you intend to generate a lot of revenue out of each potential client. Unfortunately, unless you are selling your media at high prices, and expect to get sales at those prices, Adsense is not likely to be an effective advertising medium for you. Neither will most other common advertising opportunities that operate on a per-click or per-impression basis.
There are a few exceptions to this. If you have found a niche that is both profitable and non-competitive, then it may be prudent to spend advertising dollars within it. This would work on a case by case basis.
The larger agencies can advertise competitively because with each client, they hope to generate long term subscriptions due to the sheer volume of media they have to offer. As most independent stores will not have something for everyone, a lot of your sales may be one-off purchases.
Nevertheless, it never hurts to run small campaigns, and Adsense is a good place to start. You can set your per-click rate low and your daily limit also low, just to see if something comes out of it. It is always possible to locate a niche that buyers will funnel through, but discovering them can sometimes take testing, and that testing costs money.