I don't have my site together yet, but I am just picturing myself as a consumer looking at my site. The first thing I see in the upper corner of the web page is the DNN search, so as a consumer, that would be the one that I use... Let's say that I use it to search for a product SKU1234, I am expecting a list of results that have pages which contain this text. Hopefully, one of them is a link to the buy now page in my cart. In all honesty, I think that the search on the actual Buy Now module is kind of hidden being so close to the middle of the page.
That being said, when you use a major search engine (Google for instance), and search for something, you get a list of results back. For instance, go to Google and search for "Smith Cart". You get 10-12 results back each with 1-2 lines of text. This text is sampled from the page (it's obviously not the entire page, just a couple of lines). However, with search engines, there is a META DESCRIPTION tag at the page level that you can fill out which is the text that Google would show if the tag is found. It's almost like an override for the search summary. The idea is that you could add an additional field on the product which would be what is returned in iSearchable for the search output. If the value is null, meaning you didn't fill out this field (it's optional), then we just return either your item Summary, or just the first X characters of your item summary.