I was in Iquique for almost 4 weeks after binning my bike in the atacama.
As said above Iquique is a Zona Franca so no tax. if you buy there you are not allowed to take teh vehicle out of region I or II for the first year unless you pay tax. this is the rule for locals and i assume it applies to tourists too. on all the main road out of these regions there are customs check points where they do check the paper work. i don´t know what the tax rate would be sorry. or if they do export plates.
I went down to the Zonafranca to look for parts and bike shops. there is 1 bloke that now imports bmw stuff. nothing in stock then unfortunately for me. but that is expensive.
i did see a lot of small japanese imports, and being from the UK i hadn´t seen half of then before. but vagely remember a couple of serrows, Suzuki DRZ400, coupe of honda XRs 400, 1 or 2 600s. but a lot were supermoto conversions. but all where well kitted out. there was even a yamaha 225 with a gps the size of a small TV!
Once again i can´t remember the prices, but seem to think they where competitive with europe. if not the states. if you compare this with santiago for example you would probably be paying 1.5 to 2 times the Uk price for a bike. so in this respect iquique looks good value.
If you speak spanish i could maybe email Alberto, "beto" , at
bemoto@hotmail.com.
he helped to fix my bike and was a great help all round. he may be able to give you more accurate prices.
i didn´t see many bikes for sale in the town though. if you bought a second hand bike from someone in town i assume it wouls still be cheaper and would avoid the tax question. motocross and enduros are relatively easy to find as long as you are not fussy as lots a miners with money and open desert so boys with toys and all that. but a travel bike may be more difficult.
hope that is some help. email or post if you want any more clarification or names of some people in town, that might be able to help.
cheers
mike