It’s not difficult to use email outside dreamhost.
“Picky” is an interesting word choice regarding your MX record and other associated DNS records. The bottom line is all email services outside dreamhost are going to require you to redirect your MX, and make some other misc entries for SPF, etc. I’ve never set up a domain for email on a yahoo business account but it can’t be much different than any other 3rd party mail provider.
The outside email provider that I use, provides a webpage to setup a domain. On that page they show you the DNS entries that must be made. Then there are fields that show “requested entry” vs “actual DNS record found” with red X’s and green check marks next to each entry. Since DNS changes aren’t instant, you can leave the page and come back later as you wait for your entries to propagate, once you get all green check marks you can move on to the next step.
The price you mentions seems good. My wife has a yahoo business email address associated with a non-profit she’s involved with. I never hear complaints from her about email problems, such as her sent or received email dropping into a black hole or getting blocked etc. She used to complain about yahoos mail interface, but yahoo greatly improved and standardized that in the last few years.