Thirty sounds to me like an introductory price for new Fiverr, though he/she may just be wanting to undercut. If he/she is successful and getting good gigs, I'd expect that price to rise. Two-Twenty sounds like it's probably a "Pro Certified" Fiverr account. I'm not sure how that is achieved--perhaps by reaching a certain level, or perhaps by demonstrating credible bona fides as a music industry professional, or maybe some other means.

In my looking 80-100 dollars for a vocalist for a full song seems about middle. Shorter vocals seem to hit about 20-30 USD a minute as a median.

If I had a good overall experience, I tipped well. My (Italian) sax player delivered three times more material than I requested and followed my instructions extremely well, short of my providing him charts. I almost doubled his asking price in a tip.

Geography likely plays a role. What I paid the flute team would be some padding on a week's pay for a low-end American worker--maybe a bit extra for the month. To a pair of Sri Lankans, it more nearly approached BEING a week's pay. Plus Tip. And happy to do it.

I'd be interested in your results. On the other hand, a vocal is a very subjective experience. Your 30's overall performance may be 7 and 1/3 times "better" than your 220.

BIAB 2021 Audiophile. Windows 10 64bit. Songwriter, lyricist, composer(?) loving all styles. Some pre-BIAB music from Farfetched Tangmo Band's first CD. https://alonetone.com/tangmo/playlists/close-to-the-ground