Anyone know roughly what it costs to do a pre-purchase exam in Louisiana?

Not sure in Louisiana but I've had them done in CA, AZ, TX, and they were all about the same. Only small variations. Depends on how deep you want to go. A basic flex test and wellness is about 250. Then if you want X-rays to dig deeper it goes up from there. Front feet are about 200, same for hocks. I never ever buy a horse at any price without front feet X-rays. Can save you 1,000s later. I would say you can get a good PPE for about 500

I don't think I've ever paid less than $1,000 for a PPE. I get basic exam, flexions, and lots of X-rays (including, like someone said above, front feet checking for navicular changes). 

Not a clue about price there, but wording can mean a HUGE difference in your vet bill.  I usually have people request a "Soundness Exam" and then add items to the exam based on what is discovered.  Some vet clincs have a set of things they perform as part of a Pre Purchase Exam ("PPE") and you can start at $500 and up and still add as they discover things to check.  A "Soundness Exam" usually starts out a lot cheaper and then add up.  Ask the clinic what it is for a "sounndess exam" first and then how much for x-rays, etc.  Then you can ask about the PPE and see what they include in that exam and initial cost of that exam. 

Where in LA? I'd for sure go to one of the race track vets IF you have a good relationship with one. If you don't, I'd say leave the state or at least use a vet that's not known to the owner. Also be prepared to spend between $500-1k.  

Probably 10 years ago I paid 800 for a PPE. Took xrays of front feet and hocks, plus an X-ray of a jump on his lower pastern. The vet also recommended pulling blood to keep in case the horse had a personality change within a certain time period to check for any drugs they could have given him. A just in case thing. I told him the seller had great reviews from former buyers, but he insisted we pull blood, just in case. I wouldn't be charged for the tests if we didn't need to run them and he didn't charge me for the blood pull. Thankfully I didn't need them, but I did find it curious it was a big deal to him. This vet clinic was right by a racetrack and he is a performance vet so I figured he had good reasons for the recommendation. 

I'm not in Louisiana, but I did a PPE last year and spent about $600. Ultimately, it depends what you decide to xray and ultrasound, and so forth.