I want to make a Blitz but hesitating on whether i should search for uvs or simply make one.
Advice on Blitz
Pretty much what Bamzalot said, though a CTR UV and/or an ASI UV synergise very well with Blitz, moreso than a lot of weapons.
It still is the same weapon regardless of what's slapped on it; UVs are not a need, they're more of a luxury. So if you don't have the crowns/CE to purchase one with CTR Med+ (which is the UV you should be getting unless you're using full Chaos), just make it outright and who knows, you may just get a nice CTR or ASI UV along the way.
Also be certain NOT to upgrade to Blitz until radiants have returned; keep it at Strike Needle.
I agree that there's nothing special about Blitz Needle UVs. You have to decide how much these UVs are worth to you, and how long you're willing to hunt for them. There's no rule of thumb or anything like that.
You definitely want CTR. To some extent, you want ASI. ASI lets you complete attacks more quickly, and hence promotes safety. (It doesn't make much of a difference in clips per minute, however. See data here.)
The better solution to this would be to just leave it as a level 10 Strike Needle until you are able to stumble upon enough radiants to get it up to level 5 at the very least. If you don't want to waste time at getting a brand new and shiny 5* gun then you don't need to have a UV. Though I would highly recommend getting a bit of charge time reduction since that's the best way Blitz Needles are used.