5-gallon buckets can be free or $2-3. However, they are deep, and some veggies may not need that depth, not to mention the amount of soil needed to fill it in. 3-gallon buckets may be better. Alternatively, this is a way for you to transfer and keep your bed's soil also, so it might be a good idea to go ahead and pack in your soil to these containers.

Check $1 stores for simple pots that you can add drainage holes to, but are not as deep. Some stores also have styrofoam containers. Use your imagination when you're at the store and see what non-garden containers you can find.

Also you can use the reusable shopping bags, which are also not that expensive and will come with handles. I've also planted in regular plastic grocery bags, especially if it was a temporary planting --- though I've seen the temp planting go all season and still have no problems.

Put out a want ad on craigslist or similar site for extra pots, as well as telling all your friends and family. Many people are buying the plants to put in their garden and probably will have plenty of pots free for you to pick up. I actually got a bunch of pots of various sizes from a friend who was redoing a landscaping project. If I had not mentioned it to her, she never would have known I was looking for pots.

Great ideas above. Also something to think about, what are you planning on doing with these in the future? Are they going back in the same place, you just need them moved for the construction? If it were me, and I was planning on moving them in the long run I think I would quick do a raised bed out of 2x4s that is just big enough to plant them in the new site. 2x4s are cheap and many plants can go in 6" of soil. I did mine with a weed fabric on the bottom and threw them right down on top of sod with no problems. Obviously, the sod underneath is now dead, so you might not want to take this approach over part of your lawn that you want to keep!

If you have a goodwill store try that. Many people bring their donations in storage tubs, the stores sell the bottoms very cheap.

The bakery section of our grocery store gives away plastic buckets that icing comes in. They are 3 to5 gal size. Susan

on garbage day in the morning bike or drive around your neighborhood. many people put pots out in the trash they they got their plants in but wanted to upgrade to nicer plants. Other idea of mine is build the new bed and do a direct transplant the same day or the same day and day after. If they need to sit in a planter for a bit I'd use anything I could find.... huge kitchen bowl, whatever. Also you can ask your local grocery store's bakery manager if they can save the large icing buckets they use for you ( leave your number on some post it notes for them to stick to the buckets ) or another option which is kind of ghetto but you could buy the huge home depot buckets for this, use them, clean them out and return them ( save receipt and don't get the barcodes dirty. good luck!