Hi and welcome to the Steadicam Forum, this place is a great resource of informations for operators of every levels. A lot of questions have been asked and already answered, please take some time to read through the posts, use the search option before posting yourself.
If you wish to go deeper into the steadicam world, I may recommend you a few steps (in the given order if possible) to take before throwing yourself into buying a rig.
- Buy the Steadicam Operator's Handbook. LINK You will find in it a gold mine of knowledge going from operating to choosing your rig and managing your steadicam business.
- Buy the EFP DVD LINK It is the best instructional video on how to operate a steadicam. Is is based on the older EFP rig (that a lot of operators still uses today) but is relevant for all other rigs as the physics apply the same way for all.
- Take a workshop: there are a lot of great workshops around the world. Here is a small sample, Workshops gives you the opportunity to learn from the best, meet new people with a mutual passion, and try out the rigs.
- Contact some local steadicam operators around you, they are often happy to share their knowledge with others (if they have the time) and they are a great connection for you, they might even have a rig for rent that you can start with. If you couldn't find a workshop near you, see if they can give you a private lesson to kick start you.
- Now comes the time to look for a rig, For your first rig, No need to rush in this purchase, take your time. There are a lot of used rigs that are circulating around the Marketplace on this forum that might interest you. Learn the difference between the brands and models, Try as many rigs as you can (which you cannot really do if you don't know how to operate a little already, hence the workshop) Each person has a different approach to operating and everybody's body is different. There is a good chance that you will outgrow your first rig in a few years, and that's ok. The main brands are Tiffen (who bought the Steadicam Brand, previously owned by Cinema Product, or CP), GPI Pro, MK-V, Sachtler Artemis and Baer Bel and a few others.
Now to answer your question of a cheap sled, Sorry to disappoint you but a good cheap sled has yet to be discovered.
Tiffen has some good prices you should look into for the lower range of rigs. LINK
Know that the smallest rig capable of flying the Red Epic is the Zephyr, (the Pilot and Flyer can as well but it is pushing the rig with a stripped down camera). Forget about the Arri Alexa on a small rig, not only way too heavy but it also need a 24V power and if the production can afford the Alexa, chances are they can afford an operator with a full size rig.
Also to the Steadicam Purchase, you must add the range of accessories needed for a proper use. Batteries, Wireless video, Wireless focus, Cables, etc... which doesn't come cheap either.
/!\ There also is a number of Chinese knockoffs on the market that seem more attractive at first, but a steadicam is a fragile piece of precise engineering and you will most likely regret going the cheap knockoff route as it will certainly break quickly and you will end up racking more later for a real one, and I'm not even talking about the fact that most don't even work properly out of the box.