That might be hard to find on Fiverr since it’s so closely related to a category that is no longer allowed. I don’t know-how Amazon feels about the whole “review in trade for a free copy” but they filed a lawsuit against Fiverr sellers who offered paid reviews. Since then, gigs with words like Amazon and review are often denied even if they don’t violate rules.
Since it sounds like you want to buy e mail lists, you might just have to message sellers to ask if they have a top reviewer list for sale. Look in categories like research, marketing or with e mail list keywords. VA’s are more likely to do data entry, etc. You can also post a buyer request written carefully to state that you need some who has or can research for top reviewers and you’ll pay for their research time and the list. You will get offers from some people who don’t understand and you’ll have to weed through them.