The line that matters most for a small business owner is the last one — plan for hosting, maintenance and support, not just the first build. Two costs I'd add to the list: cleaning up the data you're migrating (spreadsheets and an old system rarely come over clean) and training the people who'll actually use it every day. A quote that only covers building the first version will always look cheaper than one that keeps it running. The most useful question I've learned to ask is: what's the total cost for year one, including fixes and small changes?