I felt the same way, I was very hesitant about building my own
Budget restraints had me looking at 100Ah - those 270 and 310 cells add up fast. I figured I could add more LFE over time as
32650 cylindrical cells in a 20p module -$220 for (4) modules - $260 with a BMS to make a 12v battery.
can be wired in series to make 24/48v packs and and the appropriate BMS
IMO, almost foolproof, easy and cheap to build.
downside - only 100A but cheap enough to build more than one to wire in parallel
https://batteryhookup.com/products/new-battery-hookup-lifep04-32650-3-2v-5000mah-cells-1
Current Connected offers a Recertified 12v kit (200Ah original but used cells are now rated at 150Ah)
$570 - some Amazon prebuilt offerings seem better but this does have additional features like low temp protection and built in breaker.
https://www.currentconnected.com/product/be-br150/
For a dollar less you can buy a new 100Ah 12v SOK with temp protection
I also considered buying 100Ah cells from one of the AMYs -
http://www.powerwholesale.net/
I think the quote was $470 (+paypal fee?) for 8 cells
On a side note I saw that current connected had the SOK listed on Amazon.
I contacted them asking if they were expecting the 24v model anytime soon.
No luck there, but I mentioned the AMY offer and he offered some 270s I believe.
I responded that those were way out of my price range and just couldn't swing it since I wanted to build at least 2 batteries to wire in parallel.
They were very willing to help me out and offered some 202s that had cosmetic damage for the same price of the AMY offer.
Multiple times they told me that they were questionable but should be OK. NO Guarantee.
I took the chance and they proved to be full capacity and perfectly good.
Side/side note:
I also purchased a 8s JBD BMS. Somehow there was a mix up and I received a 4s.
I Emailed and the correct BMS was sent out the same day- no questions asked and was told to keep the 4s
I bought 8 more cells and another BMS right away
I can't say enough good things about
I'm now sitting pretty with 400Ah in my battery bank - Quite the improvement over the 100Ah Gel set
So don't be afraid to DIY if you find a good deal.
Maybe contact current connected and ask if they have any "questionable" cells on hand