The OP coin is wonderful! It has a superb strike from excellent dies. Look at the detail on the reverse. I love it!
Just managed to win today 2 other Trajan denarii. First one was a must have for me, depicting Trajan's Column. One of the emblematic ancient buildings that I needed to have on my albums. Unfortunately (for me) I lost the Column coin I was watching. (RIC 356 with reverse legend PM TR P COS VI PP SPQR). I wasn't happy at all but after a few lots another one appeared (similar design but RIC 292, SQPR OPTIMO PRINCIPI). I know they are not rare, but seeing 2 Column denarii in the same auction was quite an event for me. I managed to win the 2nd one. And the price was very decent, even if the conservation could have been better... but it is one of the coins I really wanted in my albums. Second - RIC 119 with Aqeuitas. I liked the portrait and it was cheap in the end.
One philosophy is to collect the "key dates" first so you don't run out of powder before the end, which is a common occurrence. But there's a million ways to collect, none better than the other.
Ohhh well I mean I don’t really have like a set amount. Basically I just save up for as long as it takes me to get a coin I want. Unfortunately some coins are just too expensive to spend 10 years saving up. xD I can maybe buy like 1x $3K coin per year, a few $1-2K coins per year, and then the rest $200-$600 coins every month or two.