Uvb light fixture recommendations?

Hello.. I am currently in the market for a new uvb fixture for my girl. Found the newer t5 bulb sizes online and from what I read, they r better than the t8. I was thinking if switching bc my beardie has been having some issues with eggs and I'm worried it could be due to calcium levels.

I don't have questions about the bulb..it will be a reptisun t5 10.0.. but buying the reptisun fixture toois Soo expensive! I have been searching online for fixtures to fit that aren't specifically made for reptile enclosures.. kinda overwhelmed at the different types/styles/prices..
Any recommendations for a good specific fixture not costing an arm and a leg..or just what exactly I should be searching for..(under counter/grow light/.. etc.)

Also regarding the t5 vs. t8.. should I even be switching? Is the difference really that substantial? Thanks in advance.

T5's are a good bulb but T8's are good too - it is up to you - the T 5 can sit on top of the tank where as the T 8 must go inside the tank -- so knowing that you decide on what you want to do - to me they are a stronger bulb --- so here is a website you can get a fixture from just dont use the bulb it comes w/ -- it is not for reptiles https://www.pangeareptile.com/store/images/detailed/8/t5-ho.jpg everyone is sold out of fixtures like the Zoo Med but this one will work --- I would get the 24" fixture --- they have them in stock and sell out very fast ---
Karrie