Hi there,
I am exploring my options whether I should get fish eye for my hv20 or letus mini or fish eye for xh a1 or letus for xha1.

Is there a good quality couple of hundred dollar hd fish eye lens available for hv20?

Any input would be great

If you Google "43mm fisheye" you will find a large number from $40 to about $500...here's one, I have absolutely no idea of the quality and it's not a recommendation, just an idea of what you may find:
DEMON FISHEYE LENS.COM (http://www.demonfisheyelens.com/?gclid=CMT4zJeg5ZkCFQJ2xgoddDJvSw)
/Battle Vaughan/miamiherald.com video team

Is there a good quality couple of hundred dollar hd fish eye lens available for hv20?

Century Optics makes a very popular .3X fish-eye dubbed the Baby Death Lens. I just received a rather pricey fisheye from Raynox to test on my HV20. Looks promising so far.
Raynox | DCR-FE181PRO Fisheye Conversion Lens | DCRFE181 | B&H (http://www.bhphotovideo.com/c/product/602147-REG/Raynox_DCRFE181_DCR_FE181PRO_Fisheye_Conversion_Lens.html)

I own the HV30 and am searching for a good fish eye lens to film skateboarding and have found this lens:

Opteka (http://www.opteka.com/index.asp?Page...rodID=165&HS=1)

I have heard good stuff but am not entirely sure what mm to get. It comes in 37, 58, 72 and in the link posted 43 which is compatable to the HV models. However When I got my Raynox 6600pro, I got it in a 52mm to avoid vig and CA. Should I also get a larger size for the fish eye as well and use a step up?

I also would like to use this lens with my Digital SLR which is 52mm... What should I do?

Thanks,
Terry.

I have a Century Optics .55 WA that I use on an HV10 and in great light I am quite pleased. In low light, things go a bit pear shaped. I think it's a function of the camera as much as the light getting into the lens. Just a caution.

Yep. It's not a fisheye but maybe some of the experience will translate.