Maybe it is worth looking at import duty. Here in NL it pays to keep the price of the car ex-factory as low as possible and then add options later to avoid the extremely high tax on new cars. Ordering a new car is a lot of fun but also daunting. You will probably not stop changing your mind until long after you have received the car, but it wont spoil the enjoyment of the car.
Underseal came as standard on my 2010 Roadster, it didn't in 2008. Most of the options are very a personal choice and opinions vary a lot. My 2p worth;
The most costly "mistake" I made was to buy the plus4 when I should have gone for a roadster. The upside was that I had another go at specking a car when I upgraded.
Bumpers or overriders? After the color, probably the biggest visual impact decision. I think the front of the car looks a lot better with the full bumper to straighten the lines. The back of the car looks a lot better without the full bumper because it sits too high and looks out of place. The combination of bumper at the front and nothing (or overriders) at the rear is often found on older (sixties) cars. Look at many cars and pictures before you decide.
I think the standard for the plus4 is one protective strip on the wing at the door. Two looks better, but I prefer no strips now. (as on the sport models) Cleaner looks, the strips trap water and grit, the wings are much easier to clean/wax without them. They weather easily, they are not very functional because shoe marks appear on the round edge of the wing where there is no strip. If you want to protect the paintwork better use a protective foil.
Mohair or everflex hood? Mohair is much better looking but expensive. I hardly ever use it and went for everflex again.
Sport seats with adjustable backs are a must. I just cannot get comfortable if I cant adjust the seat. I love the piping on the seats and carpets in contrasting colors. E.g use the color of the carpets as piping on the leather and the color of the leather as piping on the carpets. Dont bother with the radio preparation. All wires and plugs are there anyway. If you want a radio later it is easy to install. Wood rimmed moto-lita and wooden dashboard are ultimate eye catchers. I went for the walnut, but if I had to do it again I would choose the plain ash dashboard. All IMHO of course, enjoy the process!
Cheers J