kry226 if your worried about a used Excalibur product, I would not worry about it. Just make sure that the limbs are in good shape (no cracks) or the bow has no signs of misuse. The reurve model of rossbows are usually very dependable and carefree. If this used bow has been looked after, then I believe that you ould not go wrong with it for a bow (espically if $ is a concern). An Excalibur bow, if looked after, will last for almost ever, mine is 24 years in use.
IF you want all the stuff, then go for the new package, but ususally your old heads will work just fine with the crossbow, so you will probually not need new heads. The scopes are both good. I personally do not think you need the lighted reticals, unless your hunting dark haired animals (bear, moose ect.) but the lumi-zone does give you a wider field of view (if my memory is correct).
My suggestion for you is to make a list of what you will want for accessories and try to make a package deal for what you will need on top of just the basic bow (this will be what you want, not what they want to sell you). .............. not a slam on Wyvern, just a general statement about the comon retailer. After you do this, then you will be better able to figure out what is better for you.
But again, I personally would not hesitate in purchasing a used Excalibur product is it is in good shape and reasonably priced (if I could afford another bow
).