Depends on your budget lol. I know of a few personal favourites in the 135mm range that I have either tested or thoroughly researched. These include:
1) Tair-11A 2.8/135 (Russian funky coatings and supposed great bokeh due to crazy number of aperture blades)
2) Pentacon 2.8/135 (German alternative to No. 1)
3) The original Sony/Minolta 135 STF (Of course ler. Expensive unfortunately)
4) Jupiter-11A 4/135 (Had one, was very bokehlicious despite ONLY being f4, thankfully smaller/cheaper than 1-3 as a result. Also had Russian funky coatings)
I don't have much experience with 200s though, other than with zooms. Never really had the need to shoot much with such long teles.
There are also a tonne of other great choices in the 135 length from the named brands, with Canon FD, Minolta MD/SR being amongst the more inexpensive lines, but prices are simply just not as cheap as chips as it used to be anymore lol, thanks to the birth of mirrorless.
And do understand that while these vintages are capable of surprising levels of performance, coatings on almost all of them are far inferior to what we have today. So yeah, flares galore.
IMHO, for below 500 new your choices are limited to 2 if you want TTL (aka auto flash) AND your flash gun to be proportionate in size to your A6000:
1) Meike MK320 - Ok-ok power, features performance and build. No HSS. Available locally (KLDSLR)
2) Godox TT350S - Built in radio controller/receiver. Not sure about build quality/power/performance though. Not sure if available locally (eBay got of course)
Furthermore, like
IwanAGP mentioned, 2nd hand Nissin i40s are usually available for around 500 too. Not a lot of fancy features on the i40 but power, performance and build is great, especially for the size.
If you don't mind bigger flashes IINM some Yungnou and Nissin big "budget" flashes are also available for the Sony MIS hotshoe for around/below 500.
And yeah, there's also the HVL-F20M if you wanna stick with Sony, but other that the ability to wireless TTL with other Sony flashes, there's not much to recommend the F20M for.
Thanks! I've read some reviews on the Godox TT350S...seems like a pretty good deal...i saw some online for below...400...might give it a try hehe