I have been using Google Custom Search programmatically to search and bring back information for me. Since it is working well, I would like to get more searches per day.
Is Google Site Search the paid version of Google Custom Search, or can I pay for more searches using customer search?
Yes, Google Site Search is the paid version of custom search and with more features. Here's some comparison for you - https://support.google.com/customsearch/answer/4541888?hl=en
Access to XML API for results, no ads, on demand indexing and tech support are big plus with Google Site Search.