Check DH Gate, Amazon, and eBay for a A271-A272 tube. It’s a very good device for the cost. It will benefit from a bit of touch up filing, sanding, and polish.
Not being a wiseass here. Start saving your nickels and work a little overtime and check out Mature Metal. W/we went through a half dozen cheaper models plus a Neosteel and a Lori’s before finding MM. It may take you a little longer, but you won’t be sorry. Just my $0.02.
Don’t buy cheap plastic or Chinese knockoffs. We spent way too much money trying to buy the perfect one only to discover they were all a waste of money. Invest in a custom made metal cage with an intergrated lock. I have been locked since June in my perfectly fitting PA cage by Rigid Chastity. It took 4 months to get but was worth the wait and cost around $300.
I have one from Amazon "Happygo Male Chastity Device Hypoallergenic Stainless Steel": https://www.amazon.com/gp/product/B01GQBWENW/ref=ppx_yo_dt_b_asin_title_o02__o00_s00?ie=UTF8&th=1 It is of very respectable quality for chastity play. My only complaint would be the tip opening is a bit large... I can painfully pull the tip of my penis through... but again it doesn't happen automatically and doesn't feel good. I wear it if my belt needs cleaning or adjusting. It appears to be high quality metal, mine didn't require any sanding and it comfortably holds my penis. The only exception is my nightime pee erections... where I swell up like a balloon no mater what I'm wearing until I go to the bathroom. But nothing is comfortable for me when that happens, even without chastity its not comfortable lol. I will say a high quality expensive device is great and all, but I don't think they are the correct way to enter into chastity. You're better off testing out some cheaper ones to get an idea of what shapes, styles, sizing etc work for you. I've discovered a number of things from my cheaper devices to help figure out what exactly I need from a longer term investment.
Check out malechastitynow.com... You can get a really good fit with out spending as much as a fully custom device, but like @Blue Moon said about Mature Metal nothing like a fully custom cage. Fit is everything for 24/7 wear. A couple of millimeters can make all the difference. I reviewed the Amicus by Male Chastity Now here... https://www.chastitymansion.com/forums/index.php?threads/mcn-amicus-review.31022/
Besides a A272, I have a MCN Contender. It is very high quality, he provides excellent service, and it is light weight and comfortable.
This is great advice, experiment before even thinking about a custom cage. I've found the A273 works great for me. Maybe too great.