Before revision:  We give upper and lower bounds for the whole range of reservation costs, with tight bounds for costs up to 1/ 6---an area that is strictly 2-competitive---and for costs between 2-1 and 0.5---an area that is  (2+\alpha)-competitive . With our analysis, we find a counterintuitive characteristic of the problem: Intuitively, one would expect that the possibility of rejecting items becomes more and more helpful for an online algorithm with growing reservation costs.
After revision:  We give upper and lower bounds for the whole range of reservation costs, with tight bounds for costs up to 1/ 6---an area that is strictly 2-competitive---and for costs between 2-1 and 0.5---an area that is (2+\alpha)-competitive up to \phi -1, and strictly 1/(1-\alpha)-competitive above \phi-1, where \phi is the golden ratio. We find a counterintuitive characteristic of the problem: Intuitively, one would expect that the possibility of rejecting items becomes more and more helpful for an online algorithm with growing reservation costs.