Marcella,
Are you located in a city? If so, there are so many places to get containers!
Local, independent eateries could go through several in a day and give them to you if you asked. Your coffee shop may have milk jugs, our local soup kitchen has TONS of plastic recyclables they put just out the back door until it's time to take it for recycling, and they don't care where it goes.
And if you can't find what you need, you can always use things you can find at the dollar store. They have plastic cups, or my favorite - plastic shoe boxes. I turn them upside down and poke holes in the old "lid" (now your base), and in the clear plastic "bottom"(now your dome!). I fill small old garden containers with soil and plant my seeds and stuff as many in as I can under the dome. Best of all I can stack the clean containers inside the dome and store it all after planting!
Here's a link to someone's shoebox greenhouse below!

Here is a link that might be useful: shoe box greenhouse

I took the advice of some people who posted here and went to my local Starbucks for milk jugs. They had tons of them in the dumpster all crushed and piled up. Someone recommended pouring very hot water in the jugs--voila, they popped back to their original shape (mostly). I cut the jugs with heavy duty scissors and duct taped them closed after sowing seeds. It was easy peasy!

Also, the large salad containers with spinach, etc., are a great starter--I asked my friends to save theirs.

Good Luck--recycle, recycle!

Thanks! I'll try Starbucks. I've got family saving jugs too but not sure what I'll get and when. I've got my seeds on their way!

Nursery schools, day care centers, donut shops--all go through plenty of milk a week. Some even recycle spring water jugs.

If you have a local Freecycle, you can post it there. I just did this on Monday and ended up with over 100 jugs, which were accumulated from 3 different people.

Your local public school cafeteria - that's where one of our forum members said he asked & was given huge plastic containers that various things had come in. Your tax dollar at work!

I thought I read that you can use cups with a baggie on top & secure it with rubber bands! ALL CHEAP things (cups-baggies-rubber bands)to buy if needed. Or you can just use gallon size ziploc bags. there's info on that on wintersown.org. If you go to Sams CLub you can get gallon bags for under $10 for like 200 of them! So if you must buy containers there's LOTS of cheap ones that work well!!

I second Freecycle, but friends & family members-especially those with teenage boys! They produce milk & soda bottles at an amazing rate! Offer to trade 'mater plants for jugs at work. Some people (no... not me officer!) have scored big the day before recycle day! (This CAN be somewhat illegal-check local regulations!)

One of my neighbors brings her empty milk jugs over and puts on the front porch but if she forgets I grab them out of her recycle bin on recycle day. A few others have begun leaving their jugs on the front porch too. It's kinda fun to go out onto the front porch to see the loot that shows up on it's own!

If your city recycles you would score lots of jugs on recycle day just in your neighborhood.

I tried cups in the past and my only problem is that they dry out way sooner than jugs. Not as much mass to hold moisture in.

Unfortunately our city does not recycle. My husband got 5 milk jugs out of the dumpster at Starbucks. But I'm very intrigued by using gallon ziploc bags. Is that all you need? Please tell me how!!

Here's the link for ya.... I'm gonna try some this way too! My first thought was when it is time to plant out how do you get them out of the baggie but I read you can just slice down one side of the baggie... makes sense!

Here is a link that might be useful: ws'ing in a baggie

Unfortunately our city does not recycle. My husband got 5 milk jugs out of the dumpster at Starbucks. But I'm very intrigued by using gallon ziploc bags. Is that all you need? Please tell me how!!

I don't live in the city limits, so we don't have curbside recycling, but we do have a recycling drop-off, where I've picked up plenty of newspaper (for newspaper pots), milk jugs, and my favorite, 2-liters.

2-liters are my favorite, because they line up easily, and because I tend to get nervous planting stuff out early, and they are deep enough to leave less-hardy seedlings in a little longer. (I cut some of them short and some of them tall, so that if I end up with a tall tomato plant, for example, I will have a tall "lid" for a plant that's already in a tall container.) I also like half gallon milk jugs for this reason. (Most milk in our area comes in opaque jugs, but things like water and tea come in the clear ones.

My other favorite are the large styrofoam cups from Chick-fil-A and Sonic. Most of my friends know to save them for me, and they get fresh veggies in return when summer comes around.

What about the Slurpee cups from the local 7-11 or whatever convenience store is in your area?