Users who use search on your website convert at a much higher rate than those who don’t. On my website, the difference is striking. Visits with search convert about 500% higher than those without search.
Please remember, though, that correlation does not imply causation. The simple act of searching does not necessarily increase conversions. These buyers may simply be more motivated than a person simply browsing your selection. They may also be returning customers who want to quickly return to the product they had visited previously so that they can complete a purchase.
Regardless of why visits with search converts higher than visits without is somewhat irrelevant. The point is that a great search product is a requirement for any ecommerce site.
Depending on the number of items available for purchase as well as their degree of differentiation, your specific search requirements may vary. You may require more than basic search. You may require faceting and filtering (for example, search by brand, color, price, etc). The more complex the solution, the more expensive it will cost.
For basic keyword search, I suggest taking a look at Google Site Search. We used their system for many years. What we loved about it was that we could have the results returned as XML so that we could customize the display of the results.
Most Google Site Search implementations are ugly and awful as it appears as if a Google SERP has been pasted into your site. It’s confusing to the user. “How did I just end up on Google? I thought I entered my query on awesomestuff.com?” My suggestion, therefore, is to avoid this by actually paying for GSS (prices start at $100 / year) and hiring a programmer to customize the results and integrate it into your site design. We separated product page results from content-only page results. It made for a nice experience for the user.
Another cool search product is Amazon CloudSearch. Part of the AWS suite of products, Amazon CloudSearch is also a cost effective solution that (like most AWS products) scales automatically depending on demand. As of this writing, a “small instance” runs about $80 / month and handles up to 1 million indexed documents. That’s pretty awesome. You’ll have to do some programming to get this to work, but search is entirely worth it. Remember, visitors who use search are going to convert at a drastically higher rate.
Another related tidbit is to make sure that you’re tracking your search queries via Google Analytics. This is an easy setup procedure and can provide a wealth of useful information. You can quickly see the most popular searches on your website. Try entering them on your site to see what your visitors are seeing. You’re certain to gain insight into your visitor’s mindset and make tweaks to your merchandising to sell more product.
Bottom line: If you don’t have search, put one in. If you have search, but it’s not an indexed collection from a vendor such as Google, Amazon, or one of the other third parties listed above (i.e. some sort of WordPress plugin that is doing basic queries against your database), you’re shortchanging yourself and your customers. Proper search algorithms should handle plurals, stemming, some level of misspellings, and even customizable synonyms (gummi = gummy). And because they’re indexed, they’re far faster than basic queries against your database tables.