Just to be clear here. I'm not criticizing any of us enthusiasts who want to get the latest and greatest. I also have great respect for the bricks and mortar detector dealers out there who work hard to make a modest return. Likewise reputable online dealers are mainly doing a great job.
Paying 100% up front without solid information as to ship date, delivery method, etc is risky. Credit Card companies as well as PayPal are good about protecting the buyer (unless you pay via PayPal gift - which is pretty much like sending cash - you can't complain to PayPal since you told them you weren't buying anything!).
Even though we usually pay in advance for online orders, reputable dealers NEVER offer items for sale that are out of stock without making it clear that payment will not be due until shipment.
Even then, legally, the seller is obliged to deliver the goods to you. All risk of loss or damage prior to delivery is HIS, not yours.
I was a buyer for 35 years - and for my own use have bought way more crap than I should have.
On the other hand, advice is worth what you pay for it and this advice is free ---- and therefore worthless!!