Elisha Brooks moved to South Carolina in 1766 (deed) and isbelieved to be the son of Richard Brooks. Richard Brooks is believed to be the father of my Robert Brooks, b. ca. 1736. Both resided in Lunenburg County, VA prior to moving SC (ending up in Edgefield County, SC eventually).
Although you have Zachariah Brooks in your line, I can not see any geographic connection between your line and the Elisha Brooks line. Elisha Brooks and his son, Elisha Brooks, Jr., both had probate records in SC. For more information on these lines, go to my web site, www.rcasey.net (select the Acrobat version, Brooks Family History). I am looking for a proven descendant of either Elisha Brooks, Jr. or Zachariah Smith Brooks (or Dudley Brooks - but I have very little on him). Since your line and its connection to Elisha Brooks is very speculative, I could not assist with the costs of the testing.
I am one of the admins for the Brooks DNA Surname Study. We now have over 200 submissions of Brooks tested to date. If you are related to my line, we have two submissions for this line (assuming my research is correct). With so many Brooks line now tested, there is also a good chance of finding a match with existing submissions.
Here is the procedure for submitting your DNA: 1) go to the Family Tree DNA website; 2) join the Brooks Surname Study group first (to get additional discounts). 2) Immediately select either the 37 marker YDNA test for $149 (savings of $20) or the 67 marker test for $238 (savings of $30). Once the kit is ordered, FTDNA will send you the kit through the mail. It takes several weeks to analyze the DNA. Once your results come back, I will be glad to assist you in analyzing the results (let me know the submission number via email from my web site or update this message for all to see).