As a long-time NH fan, I can tell you that while there have been several I-5's (don't forget the hyphen) made in HO scale, none of them can be had for under $300 these days (unless you really luck out). The least expensive "real" I-5 is one of the best ones; namely, the Broadway Limited version that retails at $450 but I've seen for $360 or less:
The BLI is simply a great model. I love mine. It weighs 2 lbs., and I've hauled 14 passenger cars up a 1.5% grade with it. They really nailed the sound of the "steam boat" whistle these locos had (compare to the NH WWII film, "A Great Railroad At Work"). And even with the sound off, the engine runs smooth and quiet. Best of all, it's really, really accurate. No one has said a single bad thing about it that I've ever heard.
The other I-5's have all been in brass by NJ/Custom Brass (~$400), W&R (~$800), BLI ($1500), and PSC ($1500).
The IHC model you mention is not actually a NH I-5, just some kind of Hudson with "NEW HAVEN" on the tender...and the "NEW HAVEN" on the tender is in a totally bogus font. The tender should have two silver stripes on it, not one, and that wide stripe should be on the bottom of the tender sides, not 1/3rd of the way up it (the other, smaller, stripe shoud be along the top edge of the tender). The "S" strip under the cab should continue under the cab, not stop under the window. The drivers on the model are spoked when they should be "streamlined"...not to mention that they should also be painted with silver center discs and wheel rims and tires. The bullet nose on the model should encompass the entire smokebox front, and there should be a "skyline" casing hiding the stack plus the steam and sand domes. About the only thing they got right was the number of wheels and the 1400 number.
So if you want to start with this model and create a NH I-5, it's going to require a lot of work. It's not impossible, as there are many parts available, but it'll still be some serious work. I do not know anything about how this model runs, for I don't think I've seen one in person.
Personally, I always thought that the best starting point to create your own NH I-5 would be to start with the ATSF "Blue Goose":
Microscale makes the decals, and at least the Blue Goose is streamlined with the skyline casing like the NH I-5. A little reworking of the nose cone and front, some black paint, and the decals, and you'd have a much closer stand-in for a NH I-5 than that IHC model (which is soooo wrong). Even better, the Rivarossi Blue Goose has been out for decades, and so should be available for cheap money on eBay or at a train show.
BTW, I don't know if you know about the New Haven Railroad Historical & Technical Association. We have an excellent New Haven website at www.nhrhta.org, not to mention that if you join, you get our "Shoreliner" full-color magazine and our full-color "Speed Witch" newsletter. If you're in the Southern New England area, we go to around 15 train shows during the fall/winter/spring seasons selling NH items including books, magazines, videos, and models.
Paul A. Cutler III