Options for creating a read-only replica of a DB2 database
If you wish to use Express-C, your best options are probably either mirroring the disk and logs using an OS utility (I believe best done on Unix) or through taking backups and copying them to the standby server and then restoring them.

HADR won't work with Express-C. And I'm not sure that pureScale will either (although I can't say with 100% certainty.)

Do note that not every feature from higher editions of DB2 (such as Enterprise) won't work on Express-C. Multidimensional Clustering Tables (MDCs) or BLU for example. So if your client uses those features someone is going to have to pay for a license for another server.

I guess I would also question what data may be in that production server that a client wishes to allow you to have? Or that you wish to have? That is pretty dangerous. Developers should have limited access to production data. It should be specific and timed. Otherwise a copy with scrambled data should be restored to a test or dev environment (still preferably on their equipment). A good DBA shouldn't just let someone have access to production unless they have signed in blood so to speak. I'd go so far as to say a DBA shouldn't really even be able to see the data in production. I digress.