Depends how much you sell what you catch for. I think it can be a nice little earner a month but probably not something one should solely rely on.
No idea what people make nowadays. If you're catching to keep rather than catching to flip quickly via end user or DL you won't make any money immediately. Many of today's catchers seem to want to flip their caught domain names much more quickly. That could either be because margins are now thin and they cannot afford to keep the names long or because multiple catchers are pooling resources hence are forced to sell so everyone contributing to the resource pool gets their cut of cash.
Best you ask Nominet.
The daily lists shouldn't take you long to scour. It's the juicy out of sequence suspended domain names that some catchers go for that occur for a variety of reasons, often because someone notices a ltd has been dissolved and reports the associated domain name to Nominet. Once the domain name has been suspended some catchers have an idea of how long it will be before it drops. I also believe Nominet have sometimes given away the future drop date of out of sequence suspended domain names, or at least the date the domain name was suspended. That might depend how pally you are with someone in Nominet CS.
I think it could be easy to burn £10k on an ultra high speed setup. I don't believe any catchers are effectively their own ISPs and lonap members, hence they don't peer with Nominet directly, but twelve months of colo space, setup costs of running cables, purchasing servers, a router, a switch lonap setup and fees could wipe out that kind of budget. However most catchers seem to simply lease server space at one of a number of ISPs that they believe give them good connectivity to Nominet (via Linx or lonap), perhaps because that ISP will plug them into the switch closest to their Linx or lonap router port.
Aside from this operating multiple memberships will give you an advantage over trying to work with one. If it didn't, why do Nominet ban it in their rules? The problem with multiple memberships is unless you're lucky enough to have someone who is happy to let you use it without any expectation of a return, you'll have to compensate them some how. That can be financially or with catches or with a cut of sales. Trust me, pooling of resources and splitting of sales prices of the resulting catches occurs.
(from iPad - K)