IMO, AMD challenger quarter panels are far from perfect. Nice pieces, but the lip around the wheel well will need to be trimmed as it's to wide by about .25". The gas filler hole is slightly wrong and needs some work too. Above the body line where the panel meets the door will need to massaging to be perfect. Overall they are really good, but if you're going to OE gold standard restoration you will need to be aware of some of these things. This is just one example.
If you want a good price, call Dave at Roseville. He not only sells AMD, goodmark and more he really knows the little differences between them. No one company has the best of all panels. They each make some that are better than the other. Also consider, Year One emails out 30% off promotion codes almost weekly so that really can help if you're using them as your supplier.