I know lots of people who purchase starter websites, brochure sites, themes for CMS (Drupal, WP, Django). Those purchases are mostly in the $20 - $100 range.<p>And then there's the other end of the spectrum I've seen which is just as common - SAP, Epic Health, some Oracle-based verticals use on-site and off-site consultants to implement and customize their product offerings. Various telco and banking/finance things (SS7, SWIFT, HFT algos) require source code too.
More often than not a client will require some kind of robust charting or graphing functionality so it always ends up as a license for Highcharts.js or similar. Purchasing bespoke but robust functionality, that would be really hard to make on our own, is not a hard case to make for large projects.