Generally, money orders suck to get your actual money back, if, for instance, it gets lost in the mail. . They can take a good 60-90 days, minimum, to see your money back.
If you're wanting more control, I would ask the seller if they would be okay with accepting a personal check with the caveat that you would be fine with giving them 5-7 business days to allow the check to clear their account before they ship the product.
You can also sign up with one of the online wire services, such as Venmo, Zelle or Paypal (PP is anti-gun). Most of these services offer payment protection for a nominal fee.
Lastly, you can also send a Cashier's Check, which may cost about 6.00-10.00, but they are purchased with guaranteed funds (cash), and the seller can actually verify it's issuance. If it gets lost, you can get a stop payment on it and go through the process to get your money back. Doesn't take long at all.