eibhir,
Being a closet smoker myself (young kids and my wife disapproves of my "hobby") I occasionally only have time for a quick smoke.
If I find myself having to head back inside at a party when all the smokers are done their cigs I place the pipe in my fist with my palm covering the bowl opening and suck on the pipe for a while (time varys, you will have to experiment but it doen't take long). This seals the bowl and the tobacco goes out. Just watch you don't burn your hand! I have heard of people using a piece of cork to plug the bowl (keeps ashes out of your pocket too) or using a credit card to cover the bowl instead of your hand... equally important, don't melt your credit card!
Also, you can partially fill the bowl if you know you won't have time to smoke a full bowl, once you get the hang of packing the tobacco. Fridays on the way to work I usually smoke a half a bowl while listening to the Pipes Magazine Radio Show. Half a bowl is perfect for the drive and I can clean the pipe out before heading into work.
As for pipes, I'm new to the hobby but I don't have a lot of money to spend either. I have picked up a few cheaper brand pipes and they seem to work fine. Maybe I just haven't been spoiled by a high quality pipe so I don't know the difference yet! If a pipe smokes well for you, that's all that matters.