Totally depends on the type of training. SANS trainings (for GIAC certifications) can be done either online, or in person, but you pretty much have to take the courses to pass the exams...and those courses are 8-10 hour days for a week. It's expensive, but very hands-on. I'd rather have an employee with certifications that demonstrate actual experience and knowledge, rather than just memorization.

If you agree that the certification is worth having for your company/department, and the employee is worthwhile as a long term investment, pay for them to take the training course. They need to be in an environment where they can dedicate the time to learn.

Yeah, we've deployed this on a global WAN spanning 30+ countries, and it is rock solid. To really leverage what Aruba offers (and this is out of scope for this comment thread), you need to get their AirWave management suite. Real time and historic tracking of wireless assets, rogue detection, config management, etc. Good stuff.

You will not be able to accomplish your goals with consumer-grade equipment, simply because consumer-grade equipment is neither designed, nor priced, for this type of performance.

As a few others have suggested, Aruba Networks is a great solution, but it is neither inexpensive, nor simple/fast to set up if you don't know what you are doing. I've set up Aruba gear for a WAN spanning 30+ countries and supporting over 2000 users, and it is absolutely rock solid, with no performance problems whatsoever. The controllers intelligently move users to the least-utilized AP without packet loss, and load balance not just user count but by activity, signal strength/interference, etc.

You could pick up an 800-series controller for around $3000, but your user count might justify a 3000-series. The AP125 model supports a/b/g/n, and runs somewhere in the neighborhood of $800 each. Yes, it is expensive. The problem you are going to run into is that pretty much any AP is not going to support more than about 50 simultaneous connections, and really you are going to want to get that number closer to 25 users/AP.

Having separate SSIDs per frequency band is not a bad idea, but isn't necessary if you have a system like Aruba that does intelligent balancing.