Some of the Amvona sboxes come with speedrings (SR), some do not. I see no mention of a SR in the description of the sbox you reference, however.
If you're lucky & it does include a SR then your SR solution may be as inexpensive as $20. One type of SR that Amvona provides is very similar to Photoflex's & the diameter of the insert (the central part which actually attaches to the strobe head) is the same as Photoflex, appx 145mm. The Calumet Genesis 200 head uses a mount compatible with Elinchrom & Norman makes an Elinchrom type insert which happens to fit the Photoflex SRs. (Confusing, but worth the effort to save a few bucks...) Here's the Norman Elinchrom insert:
Again, this will work ONLY if your sbox includes a SR of the 'Photoflex' type. Remove the insert & see if it's appx 145mm OD, if so then you can use the above Norman insert.
If the sbox doesn't include a SR, or includes one of another type, then you'll need a complete SR. Two possible choices:
or (my preference, Photoflex)
You can basically use any SR that mounts to an Elinchrom head since the Genesis uses a similar mount. There are other possibilities, e.g. Chimera & some very inexpensive ones available on ebay & elsewhere.
With a typical rectangular format sbox, such as the one you've purchased, pretty much any SR that mounts to an Elin / Genesis head will work. If you later expand to strip sboxes or octagonal sboxes you'll need to make sure your SR accommodates those (both of the above will.)
Hope this helps.