Can you buy a Mac Mini with 4gb in the Apple store?

I think online only.

You might be able to buy the mini, and buy the RAM, and have them install it - but you'd probably have to wait a few days for them to get to it.
For a definitive answer, I'd call the closest Apple store.

You should be able to get in the store, but like said best bet is to check

Doing surgery on the mini is fun. I would encourage you to double think it before spending twice as much from apple.

I believe you can buy the base Mac mini, and then get them to do it for the $150 it costs to upgrade to 4GB.

You can only buy the two model listed as default models online

2.0 with 1GB and 120GB or

2.0 with 2GB and 320 GB

Anything else would be a custom unit in the store, however you can have Apple install the 4 GB of ram, you can only buy the 2.26 CPU version online direct from Apple's Online Store

RAM is the only upgrade Apple Retail does on notebooks, iMacs and minis. The prices should match the online price. It may take them a few hours (after you've purchased everything) to do the job. Check with a Specialist in the store to see how long...

In the UK they do the upgrade in store, takes about an hour as long as a genius is free. Call ahead and they will book you a slot for your 'shopping experience' and upgrade if you decide to buy.

This is how I bought my mini (early '09) from the Southampton apple store. Cost exactly the same as having the upgrade done at the online store. I payed for the mini and a RAM upgrade kit, they took it out back and I collected it an hour later all re-wrapped in its retail box.

It is cheaper than you think as you don't pay for the original RAM that they take out.

I did however upgrade my HDD myself and it wasn't that difficult, the hardest bit it getting the case open without scratching the aluminium!