Many things get called a “Meadowbrook” cart now and you need to decide what features about them are desirable to you.
Typically a meadowbrook is a rear entry cart. This can mean stepping on the floor (from the back) and OVER a fixed bench seat. OR walking thru a seat that flips up - either toward the center or toward the outside.
For comfort it is nice to have seat backs on the seat - but to make it work you need those to be folding so they can get out of the way when you need it to. These are pretty easy to install later if the cart does not have them now.
We have found that having the hinge of the flip seat in the middle - so the seat flips from the outside toward center gives you a lot more room than the seat that flips outside - which is hindered from flipping far by the fender and the wheel.
Another problem that used to happen on some older carts was that the flipping seat was not made wide enough (though it did not look too narrow) and over time the shafts would spread a bit and the seat would collapse thru the opening and you were sitting on the floor - bad!
What people generally mean when they say “easy entry”
is a cart that you enter in front of the wheel. For most Amish made EZ/front entry carts - for horses - this will usually mean some kind of step up onto the floor of the cart. Depending on how high that step is - it can have its own challenges getting into.
You may hear from people that the rear entry meadowbrook cart is a “death trap” This is because once you are in the cart, you are sitting “in” a box and there is no obvious rapid exit. Although in an emergency you are probably best staying with the cart and if you really need to bail, you are going to dive out over the wheel of either the front or rear entry cart.
We have had a rear entry “marathon” cart for more than 20 years and I love my cart. We lost our first cart in a fire and ended up buying another with upgrades and I love the new one just as much.
Cielo mentioned many things to check on but basically what you are looking for is a cart that both looks and feels solid.
Plan on re-doing the wheel bearings - that should only cost about $20 for new bearings and a couple hours of time and dirty hands.
IF the cart does not have roller bearings, you need to find out what kind of axle it has which will tell you how to care for it. In any case, a good thing to check is the tightness of the wheels on the axle. Have someone hold up the shafts and then stand to the side of the wheel - grab the top of the wheel and give it a good shake forward and back - try to make it rock on the axle (side to side). It really should not move in this way. If it does, something has worn to allow that movement.
The axle may have a hub or be a “flush hub.” A flush hub is likely to be newer. An axle with hubs sticks out about 4 inches. There is no real functional difference in how the wheel works but the flush hub is desirable for CD competition as it is less likely to get caught on things. But then a cart is no longer as useful in CD marathons because of its length and turning radius compared to a 4-wheeler.
Get measurements on the cart for the width of the shafts at the cross-bar and at the narrowest point which is where the cart shafts will sit in the harness tugs - or at the girth of the horse. You also need the length of the shafts from the crossbar to the tip. This will tell you how long a horse will fit in the shafts.
The wheels for a typical horse sized cart should be 48 inches diameter. The taller the horse is, the more desirable it would be to have taller wheels but without going into full draft carts you generally dont see larger than 52 inch wheels
You want to look at the rubber on the wheels. This can be a flat bottom or a more pointy shaped solid rubber insert wrapping around the wheel. There are some functional differences in how each tire will work but they are minor. What you do want to look for is the condition of the tire. First is it solid all around or do you see a split somewhere in the circumference that leaves a gap. Or are there big chips and gouges in the tire material. This could mean the need to replace the tire. While this is not a major job, if you are not near places that do it - it can become a big deal.
Look at where the spokes go into the hub and where they go into the wheel fellow. They should be solid and firm, and especially at the fellow - neither side should look dried out or separating.
There should be a singletree and it should move freely. If it is stiff or locked, this can be fixed with replacing some minor parts but it often says that other things might be wrong too.
The American Driving Society website has a chart on it with “typical” cart measurements and how they relate to size of horse. These should work well for this type of cart. (They are less useful for really modern cart designs.)
And by the way $450 is a great price if the cart is sound.