Regular 3DS was tiny and $250. 3DS XL was $200 and bigger.
The OG Gameboy launched for $89 back in 89. Factoring in inflation that would be $186 in today's money.
The GBA launched for $99, which is $144 in today's money.
DS Launched for $149, which is $202 in today's money.
3DS's $249 is $284 in today's money.
In fairness, you also have to take into account that the 3DS and PSP launched at significantly different eras. True, the launch price of the 3DS was high, but so was the PSP in 2005. The PSP also didn't have to compete with tablets or smartphones either
At $180, the 3DS would've definitely done better but not by too much I think. And it came out in 2011 when smartphones and tablets were already surging their way through in the technology space and eating into the handheld arena. So it was a struggle but still impressive to reach nearly 80 million despite that.