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IMHO having the primary center-spotted for you and the collimation done correctly (and having someone to demonstrate it) has to be worth the extra money.. although the collimation will need adjusting from time to time it will be much easier knowing they have already got the secondary stuff right and you should mostly just have to do minor adjustments to Primary tilt which is real easy.
You absolutely need a primary center spot so if you buy a scope without one you will have to take the primary mirror out (and probably out of it's cell) and work out how to place a perfectly centered spot yourself, I found this to be not much fun.
Bruce
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