RE: First Crossbow
You probably won't like my input but here it is. I would not buy any of those you mentioned. Do yourself a BIG favor and make a phone call to David at Wyvern Creations: 603-659-0575. He can give some guidance and honest advice on what to buy.
You can get far better CB's than those you mentioned and stay close to your budgeted amount. Last thing you want to do is buy a crossbow soley based on cost. I guarentee you would regret it in no time at all.