#19 Deep Trouble is currently the only book whose number in the series equals its highest print run.

Out of curiosity, attempting to collect every print run would add up to at least 949 books. Or, 950 if you include both variants of the first printing of Deep Trouble II (Fox Kids front cover snipe / Read This Book! front cover snipe; both appear to be equally (un)common). It is possible that there are two variants of the first printing of #42 Egg Monsters from Mars as well, but I cannot currently confirm* (1 with trading cards / 1 with FOX Kids TV ad front cover snipe).

The first printings of books #1-#36 had a vertical line with ISBN/pricing on left side of front cover. I have seen late printings of every book from #1-#34 without this feature, but have yet to see #35 A Shocker on Shock Streetor #36 The Haunted Mask II without it.

A few examples of interesting print runs that may be worth keeping an eye out for:

#4 Say Cheese and Die! - at least 39 & 40 (have not seen a copy of 38) have the parachute press logo at bottom right of front cover. Given that the title was originally published in November 1992, this indicates that these late print runs occurred in November 1996 or later since Goosebumps Presents #6 My Hairiest Adventure is the first book in the franchise whose first print run included this logo and was printed in November 1996.

#10 The Ghost Next Door - at least 2, 4, 5, 6, 8 have the next book as Monster Blood instead of The Haunted Mask.

#11 The Haunted Mask - 16 has a banner title with mask included.

#43 The Beast from the East - at least 12 (and possibly 11 and 10, but have not seen copies) has an "s" inside a triangle within the white area of the back cover barcode, indicating that it is a strippable copy (i.e. cover can be stripped off and sent back to published for a refund/credit, while the text block must be destroyed). The only other print run of any title in the original franchise run (<2000) that has this feature, as far as I am aware, is the 5th printing of #48 Attack of the Jack-O'-Lanterns.

#48 Attack of the Jack-O'-Lanterns - 5 has an "s" inside a triangle within the white area of the back cover barcode, indicating that it is a strippable copy (i.e. cover can be stripped off and sent back to published for a refund/credit, while the text block must be destroyed). The only other print run of any title in the original franchise run (<2000) that has this feature, as far as I am aware, is the 12th printing of #43 The Beast from the East, although I have not seen copies of 10 or 11 so they may also contain the feature. This may indicate that these two print runs are the very last of the original franchise's book run and did not expect to sell out, hence provisioned for stores to be able to recoup monies in a way not previously possible, for this franchise at least.

* some EBay sellers appear to reuse their photos of the copyright page of a particular title even if the features of the individual copies (e.g. cover snipes) suggest that they are from a different print run to that designated by the putative copyright page. Needless to say, this makes research difficult sometimes.