I can open a bike lock or padlock, or “masterlock”, for $65-85 during the day. Depending on the type of lock, I may even be able to do it without damaging the lock (though this is of limited use if you have lost the key). I have the ability to pick tubular locks as well as regular ones so unless your lock has a sidebar or something complicated I may be able to pick your lock so that you can use the lock if you still have the key but lost a copy.
I do not accept any responsibility for what happens if you do any of the following:
If you would like to save money, have extra time and think you can do this yourself, one can get a hacksaw, angle grinder or boltcutters for a reasonable price at some place like harbor freight. Though I wouldn’t advise it, you could use a dremel tool to cut through a bicycle lock. You could also just hit a cheap masterlock with a hammer or pry it off with a suitably thick and long screwdriver or other implement suitable for prying. Thieves like to use a carjack to get u-locks off, and to get a chain or cable lock off they will twist the bike over and over until the cable snaps. This is why it is good to use a good lock, but also park in a public area where these shenanigans will not go unnoticed. You can also do these things but hopefully you have proof of ownership for the bicycle in case the police come.