Most of the "birth pools" have two versions - the personal ones are guaranteed only for one birth, the professional ones are for 10 or 20 uses with a new liner each time. Their plastic is thicker so more resistant to leaks and more durable but otherwise they're the same dimensions etc. They're less than double the price so if you had a friend also planning a water birth they could be useful to share and spilt the price or to sell on!

The professional ones are most likely what midwives who supply them for clients would be using.