anti-lag requires a ECU capable of doing this along with other associated a parts such as a modified throttle body in some cases, if you are going to run aggressive anti-lag I would suggest getting a maram shafted turbo as the life expectancy of your turbo without this will be reduced greatly.
If you do not have after market management capable of doing this, you should be able to get this whole lot done by most popular tuners depending upon the choice of management.. expect to pay £1k upwards for management with Anti-lag fitted


The roll cage you can get from Safety Devices, http://www.safetydevices.com/
unless of course you want one of those over sized bling 'show' cages.. in which case you would want fusion found at http://www.fusionfabrication.fsnet.co.uk/rollcage.htm

The cost of a decent cage would depend upon if you wanted bolt in cage or weld in cage, door bars, etc... call safety devices and talk to the people who know.
Alternatively you could get someone who specializes in fabrication to make you one to suit your needs