Rob contracts to make a new customized guitar for Carlos in return for Carlos' promise to pay Rob $5,000 on completion of the work. After spending $4,000 on the job, Rob fails to complete the guitar because he has accepted an offer to be a roadie for a Jimi Hendrix cover band. Carlos has the work completed by another guitar maker for $2,000, increasing the value of the guitar to him by a total of $4,500, but he loses $250 from a booking for a solo guitar performance because of the delay. How much can Seller recover?