Greetings, and welcome to the forum!
If I have it correct the MLA-30+ is an active receive only loop consisting of a small box containing an amplifier, and the loop itself appears to be either stainless steel or maybe aluminium wire?
The tripod itself need not be expensive, I've bought a number of cheap 'shopping mall' tripods over the years and all have been adequate to support lightweight loops.
Something like this one >>>
Amazon Tripod would be fine (I just posted this link as an example).
What you will need to do is modify the tripod. Where the mounting plate is for the camera you will need to remove the entire 'head' assembly (this is the top section with the adjusting/locking arm). Normally it is just one screw securing it in place though sometimes you also have to fully unscrew the adjusting/locking arm as well.
Once the 'head' has been removed you will generally see the top of the telescopic pole containing a plastic insert. Normally the plastic insert is the same diameter as the tube, so this can be left in place.
To support the loop you need to get a length of plastic water pipe, or you could possibly use a length of wooden broom handle (if the loop is only to be used indoors, outdoors the wood will absorb moisture and could affect the performance of the loop).
Depending upon the diameter of the tubing to hand, or maybe just purchased, you will either be able to slide the plastic tubing over the aluminium 'pole' sticking up out of the tripod, or maybe you will need to secure it to the side of the protruding pole. Either way you need to fix the plastic tubing to the aluminium pole sticking up out of the tripod, but only overlap them enough to give reasonable support. Don't run the aluminium tubing all of the way up to the top of the loop as this again might affect the performance of the loop.
From the photos I've seen, all that is left to do is to mount the loop amplifier box to the lower end of the plastic tubing, and then find some way to attach the wire of the loop to the top of the plastic tube. Just alter the spacing so as to give you a roughly circular loop. Some folks drill two hoes in the top of the tubing and pass the wire through it, others drill one hole and then use a cable tie to secure the wire. You could also cut a small notch in the end of the tubing and put the wire in to the trough of the notch.
If you want to go really crazy with the plastic support you could also have a cross piece in the middle with two side arms to support the left and right sides of the loop.
There's quite a few images around the web for plastic tubing supported loops (I'll add a few links below so that you can get a better idea).
Single plastic pole
Another single plastic pole
MFJ produce a portable magnetic loop antenna which uses a plastic 'cross' made from water pipe fittings which gives extra support. Although this is not the same kind of loop as your active receive loop, the support system could work just the same.
MFJ Loop support cross
If the loop is indoors a cheap tripod will support it no problem, but if you want to set up the loop outdoors then you will need to fasten the tripod down somehow, maybe with some tent pegs or wooden stakes driven in to the ground and fasten one to each leg, or, another method is to hang a weight from the middle of the tripod frame (maybe some house bricks or bucket of sand etc.)
Why the extra support outdoors? Due to the wind loading of the loop it will act like a sail, and any gusts of wind will tend to cause the loop to topple over.
The plastic water pipe can be obtained from any DIY store.
Hope that lot helps!
73, Mark...
