From my perspective prices and demand for depression glass peaked in the early-mid 2000s, after collectors collectors started buying online and before everyone rushed to clear stuff out of their attics and and expanded supply. We see that on a small scale looking at Block Optic pricing.
It’s interesting to see how popularity (which drives prices) changed over time. I am using 5 reference books dating from 1970 to 2010, plus using eBay sold items and Replacements’ asking prices for current approximations. Note all prices are assumed to be for glass in excellent/mint condition. All damage greatly reduces value.
First the more common pieces which zoomed in price between 1970 and 2000 then have roughly stabilized.
Pink Block Optic Cup
1970 $1.00 to 1.50
1971 $1.25 to 1.75
1981 $2.50 to $3.50
2000 $7.00
2010 $8.00
2017 $12 to $25, often with saucer (prices include shipping)
Pink Block Optic 8 Inch Plate
1970 $1 to $1.25
1971 $1 to $1.50
1981 $2 to $4
2000 $7
2010 $7
Now $8 to $14
Less common pieces show similar changes, a steady increase from 1970 to 2000, before dropping or for some pieces, remaining about the same.
Pink Block Optic Center Handled Sandwich Server
1970 Not listed
1971 $4 to $6
1981 $15 to $20
2000 $75
2010 $50
Now $60 (Replacements asks $32 for the round server.)
Pink Block Optic Water Goblet 5 3/4 Inch Holds 9 Ounces
1970 $2 to $2.50
1971 $3 to $4
1981 $8 to $12
2000 $32
$2010 $25
Now $22 to $34 (eBay)
Pink Block Optic Candle Holder – Set of 2
1970 $1.50 to $2.50
1971 $3.50 to $4.50
1981 $18 to $25
2000 $80
2010 $60
Now $88 (Replacements)
Although each pattern and color follows its own price trajectory sometimes you can extrapolate trends from one pattern to another but don’t rely on this as anything more than rough indicators for your own glass.