Here is my personal philosophy for collecting:
Buy, but never sale. Build your collection around three principles; time, space and money.
Time: I'm retired so I have as much time to spend on collecting as I want. There is the time spent finding, researching, cleaning or repairs, documenting, displaying and/or storing. As a collector I’m also preserving a piece of time. A time when that particular knife was created by an individual or company from today, or many years ago. I’m preserving the skills and artistry of the knife maker that went into creating that particular knife. I’m preserving a piece of history.
Space: How do I want to display or store my knife collection? This can be a limiting factor in the size of or type of knives you collect. Also it will be another expense for shelves, display cabinets etc., unless you just plan on putting them in boxes in the back of a closet.
Money: Of course this is the most important detail in your collecting. Most of us don’t have an unending source of money to support our collecting habit, therefore I believe it is very important to exercise good judgement in your purchasing choices. You can’t buy every knife out there that you like, although many of us have tried. Don’t spend the rent money on a knife just because it’s there and you want. Research and have many sources to find the knives for your collection.
And finally, remember that collections of any items are not born overnight, but over time. Learn about the many different types/styles of knives; be prudent in your knife purchases and most importantly have fun and enjoy your collection.