Need is relative ...
I think you want one eventually, a food saver or what not ...
It's absolutely not necessary in the beginning, though ...
The little ZipLoc bags w/ the little port w/ the little plastic suction thing are great ... I use the shit out of mine ... in fact, if you look at my cooks since folks have gotten back into sous vide, I've used them exclusively ...
So, no ... I do not believe you need a vac sealer IMO ... like a Searzall, it's a good add-on down the line, though ...
The Anova and Sansaire are both highly regarded. In my case, I liked the outflow port of the Sansaire - and well, the design (sleek, black, blue led) ...
Get in there, man!