I've done cash or personal check (its a small community!) but I think now I'd probably do cashiers check. But before I did that I'd probably ask the seller what they'd prefer, in case they didn't care.
I've always paid with personal check, even at an auction (although I was pre-approved when I registered as a buyer before the auction). The most I've ever paid was $25,000 and I was actually surprised they'd take a personal check, but the horse was at their trainer's and I guess they figured he was in a safe location.
I did call on a horse one time and was told they'd accept PayPal.
I ended up paying cash. (I did ask the seller) It was actually kind of cool...my bank is not local and I had no idea how I was going to get access to money on short notice...they usually have to mail cashier's checks and you can't exactly go tho the ATM and withdraw that much, ya' know? WELL, I called them and they raised my ATM/debit limit for a few hours so that I could go to the counter at a local (another company) bank and withdraw the funds against my card. It was awesome and worked seamlessly. Cool!