I have been looking for buggy locks online having just pre ordered a bj summit x3. I thought most of them looked a bit flimsy then I saw Kryptonite cable. It's a plastic coated cable with loops for a padlock. I ordered a 4ft one but they also do a 7ft which is thicker too.
It's arrived today and its really substantial! I'm going to use a code lock with it so no key required.
It was competitively priced with pram locks, maybe a tad more but very robust in comparrison. It would stop an equipped theif but is certainly good for opportunistic theft prevention.
I purchased from amazon. Hope can be useful to someone!