Here is a break down in price for single game Opening Day prices, courtesy of Mets.com:
In contrast, for Wednesday, tickets for April 3rd's game against San Diego (the second home game of the season) start at $12 for Promenade Outfield and go as high as $125 for Metropolitan Gold.
The price disparity between Opening Day and the rest of the first home series is not abnormal. What does seem excessive is the high prices for Opening Day. I assume the goal is to price Opening Day tickets so high (on their own) that they motivate people to buy the comparably-priced Holiday Four Packs. For instance, four Thursday afternoon games (April 4th against the Padres, April 25th against the Dodgers, June 13 against the Cardinals, September 19 against the Giants), known as the "Matinee Pack." For comparative purposes, a Baseline Silver ticket to all four of those games by taking advantage of the pack would be $179, which also includes a ticket to All Star Fan Fest at the Javits Center. As you can see on the chart above, that's only $10 more than the single game price for Opening Day. So the intention, right or wrong, is that - by bumping up the Opening Day prices - it makes the four packs more attractive. As a result, the Mets would stand to get a bigger turn-out for games that are more difficult for people to attend (because of school, work, etc.).
On a personal note, my father and I attend Opening Day every year. He has issues with heights, so we spring for field level seats. I don't usually balk at typically inflated prices. However, these prices raised eyebrows in the Erni family.
In fairness to the Mets, they've done a good job making tickets actually available to fans who want to buy seats prior to the holidays as gifts for loved ones - an opportunity I thought they had been missing for a while. But, the push back they've been getting on the single game Opening Day seats seems to have made this strategy of pushing the four pack plans over single game Opening Day seats an ineffective one.
It's worth noting, you could not buy Opening Day seats last year as a non-plan holder before March, when Flushing Flash, Club Mets, and other presales opened up just prior to tickets being put on sale to the general public. I would rather have seen the Mets reward die hard fans looking to lock in to Opening Day roughly four-and-a-half months in advance, than artificially inflating prices to ultimately drive up attendance on less desirable dates.