Valley View Vapes are selling pyrex tanks really cheap. If you look in the tank review section here on ECF you can find my review. I got two 7 ml clear pyrex models a couple of weeks ago, under $15 each. Width is the same as the SB. Pics on my SB are in the review.
These are silicone grommet, and utilize no end caps. They come pre-assembled with a Boge carto of your resistance choice. If you buy additional cartomizers from him, he will prepunch and test for DOA/correct resistance for $1 more.
To (re)fill these grommet tanks, you insert a blunt or plastic needle between the grommet and carto. The grommets are soft and vulnerable to tearing, so care is advised. I recommend filling from the connector end so if you do happen to damage the silicone, it won't be as noticable. The needle likely will pull a small part of the grommet into the tank with it, a dental tool can tease it back into place. Advise getting additional grommets/O-rings for like a dollar per set; your gonna eventually need them anyway.
These pyrex tanks are available in 4 and 7 ml size, frosted glass available for additional cost. A very cost effective way to get into pyrex tanks. Extemely sturdy on your mod, these will never fall off accidentally, and won't leak. A little of a pain to refill, but I've done it twice now without tearing the grommets. I recommend.