Not really my cup of tea, however when I level my alt sci captain to RA, I'll definitely want a few of it's parts to enhance my Recon Sci Vessel. Just like I did with Imperial Assault Cruiser. God awfull saucer and neck, but pretty good looking nacelles and pylons.
Most of the items can only be purchased once. Examples of items you can purchase multiple times are Renames, Retrains, Character Slots, etc. For the rest, the "Buy" button won't highlight on the interface in-game if you've already purchased the item you've selected.
Wait, I should add to this that (unlike the other selections) the "Pakled" playable species will not give any indication that it has already been purchased. It does seem possible to purchase it multiple times by mistake.