If you're comfortable working on your own ride, I'd recommend compiling the parts lists from the dedicated threads within this forum. Source the parts on your own (a lot of us use BAM Wholesale, but there are plenty of vendors out there to choose from), and install everything yourself.
The dealer likely will not be able to add the sales codes for several of the options that you're looking to add, but as mentioned above, you can make the configuration changes on your own with the use of AlfaOBD. It may seem overwhelming at first, but with some reading and patience you'll see it really isn't that difficult to do.
Best of luck!