What rights does Michelle have?

Senario

Michelle is at University, studying to be a veterinary surgeon. David, a close family friend is also a veterinary surgeon. Whilst away at University, Michelle received a letter from David on 1st April, saying that he was due to retire in a few weeks' time and that he wondered whether she would be interested in buying his veterinary equipment for the bargain price of $5000. His letter asked for a reply by 15th April as a junior partner, Peter, in his veterinary practice was also interested in buying the equipment, albeit at a higher price.

Upon receipt of David's letter, Michelle decided that she would like to buy, but would need to borrow the money. In order to speed matters up, she then wrote to David on 2nd April expressing a firm interest, but asking if he would be prepared to accept payment by instalments. Her letter got lost in the post and was never received by David.

Not having heard from David, Michelle arranged a bank loan and then posted a second letter on 9th April, enclosing a cheque for $5000. This letter only reached David on 17th April.

In the meantime, David had changed his mind about selling her the equipment and sent her an email on 10th April retracting his offer to her. He sold the equipment to Peter on 16th April.

With reference to the case situation above, discuss, using decided cases to support your arguments, the contractual implications and the remedies, if any, that Michelle might be able to pursue against David if she so wished.