Uh, I’m sure you are, but just in case, you should be replacing that every three months or so, or sooner if the bristles fray, according to the ADA.
But anyway - you don’t need to spend even 40 bucks. The one I use is about twenty on amazon(I got it on sale for about fifteen), and I buy generic-but-identical oralb imitation heads(about 16 bucks for a pack of 20, swap the head every three months), despite initial outlay I’m ahead on the whole deal by a pretty decent amount. 20 $5 toothbrushes is a fair amount more than $16 for 20 heads.
And better than doing it with a manual toothbrush, but let’s not split hairs.
I don’t know. I’m not a dentist, but from the dentists I’ve known or been a client of, all have recommended electric toothbrushes unconditionally. Personally? My dentist recommended it, and now, I prefer it presumably because I’m used to it now. I use a manual brush when I travel, generally, because it’s less weight and space to lug around.