I have chimed in my opinion in other threads, but it's seems like no one has hinted at this yet so I'll add it in.
I've purchased 6 tubas in the last year.
All of them used. In my quest for looking for a new tuba, I strongly considered going to buy one of the 3+1 EEb from a various sellers of them. Two sellers in the US made the top of my list. Jim Laabs is closer to my location (would cost less for shipping) but Mack has a better reputation, service and answered all my questions promptly. Tom, was even willing to change his order last minute to accommodate me. Ultimately, I decided I would pass.*
Why?
To me, being sorta young, cheap and with a very modest income, I view all my purchases as a investments. New tubas are not investments, they are liabilities. If you buy a new tuba, you will unlikely be able to sell it for the price you paid for it. As such, If someone were to need cash quickly, they would have to take a loss on these instruments. The amount might not seem like much ($200-300, maybe) but when one adds to that, the costs of repairs, maintenance, mouthpiece purchases, lubricants, cleaning products, etc. The loss might be more substantial. With a used horn,(assuming it was purchased at a reasonable rate) one can easily sell it a price that covers all the money put into it. One could even add the cost of inflation to the value of a used tuba.
Ultimately, I ended up buying an B&H EEb off of eBay. The price was good, but it was over $1000 more than I would have paid for the Mack EEb. However, I feel that in 5 years if I decide to sell it I could sell it for $500 more than I paid for it to match inflation and repairs/modifications that I might want. The Mack tuba, in 5 years, will not sell for more than a new one will cost at that point. It will probably have to be at least $200 less than a new one. All that money will be lost. Will it be a big loss, probably not (Maybe $400-500?). But, to me, any loss is a loss. Some people consider Tubas as hobbies, they have the money and they don't mind putting it in. Some people have full that jobs and they can afford the luxury of buying all the tubas and accessories they want. I'm not in that situation yet.
I doubt this will be the only tuba you will ever buy. If you decide to buy a tuba, choose wisely, you probably don't have hundreds of dollars that you can throw out the window. That said, bad purchases can most certainly be made with used horns.
My Advice: Look at some used horns, contact some of the repairmen and sellers of used horns on this board. Try more tubas (Including the Mack ones). Ask around (local tuba players, trombone players, high school teachers, community bad members) If you approach people politely and with some kind of recommendation(from a teacher), some local people might be willing to let you try their horns. No two horns will be identical, but I would not buy a $1000+ tuba without at least some kind of idea as to how it might play. Ultimately, you might want to invest in a trip to one of the conferences where many instruments will be displayed.
*In the spirit of full disclosure, I must say that being in Canada poses an extra challenge for buying horns. Any new horn almost always has a $500 price added to it if it comes from the US. Shipping is about $300-400 through courier services (UPS, FEDEX, DHL, etc) (Greyhound doesn't cross the border and driving 16 hrs roundtrip to the closest US station isn't economical for me) Customs and taxes add another 10% where I live. 5%-15% in other provinces. That doesn't add up to a price tag that I could view as an investment.
If I lived within reasonable distance to Mack brass I might view it differently. I might even own a Mack EEb. In reality, I don't and I really like the B&H EEb.
