I got fed up with custom orders, especially when I was buying expensive records for clock requests, then not getting the sale. Only a couple of customers even bothered to reply and say they had got something else!
Now I use the etsy custom order forms, you can "create a custom order" from any etsy email enquiry. This gives you a chance to invoice the customer before you start any work, at an agreed price. It creates a private listing which goes straight to your customer , not into your shop, and etsy don't charge for the listing until it actually sells. Some customers have still waited 2 months before going ahead with an order! but they have ordered!
Some customers have unrealistic expectations on how long it can take to create a custom piece, so it is important to give them a time frame. also if doing design work, to state how many hours. or changes to a design you are prepared to make for the price you charge.
Custom Listings, they are easier to create than they look. Just give it a go, would recommend to everyone, has removed a lot of my custom order headaches and now I get paid upfront for everything before I spend a penny!