You are not alone in this department --I do it all the time. You can find some really great pots and garden items for very little money this time of year. As for your Mandevilla they are fairly easy to over winter. I cut mine to the ground, put the pots in the basement and water them very little. Starting in March i start to water and fertilize and by may they are ready to go back outside. I have done this for several years and they just keep getting nicer. I do the same thing with a lot of my annual pots and have great success and more money in the spring to buy more orchids instead of replacing annuals.