"Costs are fluctuating daily as manufacturers and distributors adjust to limited supply and high demand," reads a message posted in the store's display case, as spotted by Steve Lin. "Because of this, we can't display fixed prices at this time." Micro Center is apparently doing the same: "Due to market volatility, we ask that you please see a Sales Associate for price," reads an in-store message captured by Redditor CassTexas (via Tom's Hardware).
DDR5 isn't normally associated with AI accelerators. Those typically employ GDDR or HBM, which trade capacity for the higher bandwidth required for those workloads. However, the systems into which these accelerators are deployed do use DRR5 for the system memory to feed the CPU and to store intermediary data, like the key value caches used to prolong a model's short-term memory over extended periods.