As a flow core cytometer facility director at the University of Chicago, I buy lots of equipment—undoubtedly more than the average researcher. Based on this experience, I wanted to present some tips to avoid buyer's remorse, see through the marketing spin, and make an educated decision on which instrument to purchase. These are the same steps I go through whenever I'm in the market. The fine details may be specific to flow cytometers, but the principles are apropos to buying any sort of technology that requires an NIH grant to buy.
#1. Define your needs. What are the applications you will run on this system? How many parameters (realistically) do you run on average? How many parameters will you run in the near future? Are there any specialty dyes you run? Do you prepare samples in tubes or plates? At what event rate do you run your samples?
Example: I have some projects in mind which require 8–10 fluorescence parameters. At 3 parameters per laser, I probably need a three-laser system minimally. I like to stain/run my cells in a 96-well plate, so a plate-sampler option is needed. My experiments typically involve immunophenotyping rare subsets, so I collect 106 cells at rates of about 15,000/second. I don't need to sort.
#2. Query the end-users. If others in the lab or core facility will use the instrument, ask them the same questions as in #1.
Example: Another user in the lab does a lot of screening of her mCherry transfected cell lines. She doesn't collect a lot of cells, but screens many samples. She would require a yellow/green laser for excitation, and fast 96-well sampling capabilities.
#3. Refine your needs. Combining the information you learn from steps 1 and 2, you should be able to refine the needs for this instrument. Annotating this list, and possibly triaging needs and wants will be very helpful at this point. Of course you are working within a budget, so you'll certainly want to keep that in mind as you survey the market.
#4. Survey the market. You probably already have an idea of the "big" players in the market, but even if you didn't, simply typing the query "flow cytometer" in your browser brings up nine different instrument manufacturers within the first two pages of a Google search. You can follow these links, collecting information on the various instruments. For something like this, I like to use an electronic note-taking application such as Evernote to keep everything together, and make notes as I go through the process. For those web sites where information and materials are not easily accessible, sending an email to a local sales representative will get you all the marketing materials you could ever ask for.
#5. Learn how to read marketing materials. Speaking of marketing materials, there are a few things you should be aware of. Beyond the very basics (lasers available, number of detectors, etc...), much of what you see in your average cytometer specification sheet is useless information. It's basically a list of values for meaningless metrics that MUST be put into the materials to match what the competition is stating—for example, the ever-present detection threshold of FITC and PE. Most all spec sheets will include something like an MESF Detection Threshold of <150 for FITC and <100 for PE. This means absolutely nothing in terms of how well the system will work for your applications let alone how other colors will fair. You'll also see outrageous specifications for event rates, like 100,000 events per second! Lastly, and probably my favorite, is the panel of histograms showing the resolution of multi-intensity hard-dyed beads (e.g., 8-peak Spherotech beads). You can pretty much ignore all this information, and focus on the things that matter. How many lasers? How many detectors? Can you upgrade the system in the field with more lasers/detectors? Is there a multi-well sampler? And, so on.