Random thoughts...
Nice. I have built the 67s now 3 times, and recently my brother finished up. It's a FUN journey if your patient. I actually have a spread sheet that unfortunately is now 3 years old and outdated but I used my prior knowledge to set goals for each high number. I had a routine -
* Twice to three times a day...check BIN's Newly listed (you'd be surprised at how many times someone will list something undervalued, they won't last long as lots of people are watching high numbered 67s every day)
*Twice to three times a day check what auctions are ending (deals to be had SOMETIMES, and there is a random "set break" from regular folks)
*Keep tabs on all GM auctions (he undergrades and is well known for great cards...although most auctions end higher than goal amounts...sometimes...haha)
*Obviously kept tabs several times a day on the net54 BTS...although so are many others! haha
The last set I built, my current set, I was patient enough to not overpay on any cards...but I was patient and not in a hurry. First couple of sets I would cave and over pay on certain BIN's. The key is to know the tough ones...Brooks, Shannon, Clendenon, Wills, Bunning, etc...and all that goes out the window on Carew and Seaver. On those...buy graded. Way too many scams, soaks, overgraded on raw to be trusted. On my current set I ended up buying a 4 on Seaver, and a 5 on Carew...and freed them both (I don't care about resell) but now wish I would have kept them graded and bought reprints for the binder. In the past I have bought a few Carews that were overgraded on raw and got burnt.
Also, fyi...the semi highs aint cheap either. Most lots you will buy to fill the first couple of series will most likely will not included any cards after #458...and 458 through 533 carry an annoying premium as well. Mazeroski, McCarver, Marichal, Schoendienst...and others...add up. In the highs, I have noticed even the DP cards are being gouged...anyhow...even talking about the 67s make me want to build another one!
Cards to just spend money on...Brooks Robinson for sure. You will be hard pressed to find a deal. Find one you like. Buy it. So many are trimmed, etc...consider graded. Niekro RC...same. Last card...Tommy John...find one and buy it. Tough to get a deal. Red Sox team...yeah...good luck. Haha.
Good luck! PM me if you ever want an opinion...I miss building 66 and 67! I currently have two sets of each and look at them routinely...once built...you feel like you have epically done something and the appreciation is through the roof.
EDIT TO ADD - I build my 66s and 67s sets at EX to EX+...no creases, ink...sharp corners (lax on centering to a degree) for every series but the highs. Highs I would not go anything that would grade under a 4...still no creases ( I HATE creases!) but the corners can be a bit soft and again, lax on centering. I'd like to think all my 66 and 67 highs would grade 5s or 6s, but I'm sure I have several 4s and for sure a few that would end up 3s...but always looking to upgrade those. So my thoughts are definitely coming from a mid grade set collector...