The Mac Studio starts with 36GB RAM, but there were upgrades ranging from 48GB to 512GB, with the higher tier upgrades limited to the M3 Ultra chip. Now there are options ranging from 48GB to 256GB, with wait times into May for the 256GB upgrade.
Apple has also raised the price for the 256GB RAM upgrade option. It used to cost $1,600 to go from 96GB to 256GB on the high-end M3 Ultra machine, but now it costs $2,000. 512GB was $4,000 when it was available.
Apple has likely removed the option to purchase 512GB of memory because of global DRAM shortages that have dried up supply and caused prices to soar, and it's also probably why shipping times for a configuration with 256GB RAM range into May.
Demand for the Mac Studio has increased due to consumers seeking machines suitable for running local AI agents, which could also be a wait time factor.
Memory scarcity is already having an effect on DRAM pricing, and it could affect PC and smartphone sales in the months to come. Apple is able to absorb higher memory costs in the short term, and it is well-positioned to minimize the effect on consumers because it is better able to secure available DRAM supply than smaller companies.