Personally I use Zoho. They have a (ridiculously) large selection of apps available, and their support seems good as well.
I'm currently using the Invoice app, and will be upgrading the CRM soon. Fantastic mobile applications (as well as a powerful browser counterpart) easily make it easy to make & track quotes, invoices, expenses, etc. I like that I can scan/add my Vehicle Inspection Forms and physical expense receipts & attach them to the customer invoice or expense note.
I'd give it a try - it's free for up to (5) customers, but what I did when I first started was made a "Quotes" customer, then in the Reference column put in their name and basic vehicle information. The search function allowed me to easily find quotes I had done up for them, and the integrated commenting system worked great for posting updates to refer back to at a later date.