 I have recently purchased a 10 litre semi-opaque (grey) plastic container which appears to be ideal for sous vide cooking. It was sold as food grade, freezer & microwave safe, and has all the relevant marks on the bottom to confirm this rating. It is manufactured from polypropylene and is (PP5) graded. Looking online, all the other sous vide baths I see are manufactured out of much more expensive polycarbonate, and this container was a fraction of that cost. I assume here that polycarbonate has been chosen because it is more rigid than polypropylene. I have tested this up to 85 Centigrade and the walls of the container flex and bow only slightly more than they do when cold. I doubt if I will sous vide beyond 75 Centigrade, am I taking a risk using this product here? 
At distribution level products can have varying quality grades and corresponding prices, and stores may purchase both higher and lower grades for sale - though it's common that the packaged-for-retail units will be higher quality in terms of uniformity and appearance, while the lower quality units are sold in larger bulk quantities for further packaging or use as an ingredient in store. There are completely separate barcodes and product codes for these purposes. However, a packaged product sold at a previously negotiated specification should meet that specification between batches. What could have happened was the store purchased the product, which normally exceeds minimum quality specifications, and found it of poorer quality due to batch variation, but within acceptable specification from the manufacturer - they took the loss or got a credit for a markdown to clear inventory. You can always ask the department manager for the reason for the markdown.  Greybeard: What about items that come in pre-printed manufacturer packaging "3 for 1" etc? Economics would suggest that these items are a lower quality, yet being passed off as the same quality as the single, more expensive product? Answer: That's a question that comes with a lot of answers based on the retailer, producer, agreed upon specifications, etc. Products like household name-brand cereals, dish soaps, etc. that come in "Family Size" or larger bulk/multi-unit packaging are the same as the smaller counterparts, there's just lower per-unit profit. These are available based on consumer psychology and retailer demand - consumers receive better perceived value for dollars spent, retailers catering to that segment like Costco almost exclusively stock these value sizes, and the producer, while making less profit, still generates revenue instead of no revenue at all in that market segment. The inverse is also true, where upscale retailers and producers may avoid these value sizes due to the perceived "cheapening" of their brand. That being said, certain discount retailers will have specifications and purchasing decisions based solely on lowest cost and cater specifically to that segment of the consumer population. The products they purchase may also be produced by licensed manufacturers of name-brand products, though failed to meet the brand specifications and were sold as off-label products; or, were sold by the name brand company in packaging formats specifically for retailers in that market segment. Durrah's scenario sounds like a product from a smaller scale producer, likely without supplier guarantees for uniformity of incoming meat specifications or using smaller scale farms with much greater variability, and are unwilling or unable to incorporate trimming/processing for better uniformity or quality control. 