So as I understand it and I am not an accountant, but there would be the potential of paying tax on the ‘gain’.
However, between the original purchase price, the cost of items purchased and the cost of work put into it (did you save receipts?), and a cost for your time for any work done (what might your hourly rate be? $50 or $75/ hr?), the likelihood of you actually making a gain is unlikely unless you are selling a very high dollar hemi car and bought it cheap.