Collecting the core Harvest Moon era on a budget
The budget fact that organizes everything is regional. The Japanese originals, Bokujo Monogatari on Super Famicom, Bokujo Monogatari 2 on N64, the PS1 and GBA Mineral Town games and the GameCube pair, were normal releases at home and remain priced like it, while their American counterparts carry nostalgia premiums of very different sizes. A collector who buys the Japanese boxes first gets the original art, the fuller manuals and, in the Magical Melody case, the more complete game, for the smallest money in the lane. Language is a real cost, but these are games whose systems fans have documented in English for decades.
Second, spend on matched completeness inside the common games before spending on any trophy. A complete, version matched Back to Nature pair, the four box Mineral Town GBA set and clean GameCube copies of A Wonderful Life and Magical Melody form a shelf that looks finished and plays completely, for less than a single high grade American SNES box. The checklist entry in this section exists to make that money count: manuals, obi cards and inserts verified before payment, not discovered after.
Third, buy the paper while it is cheap. The Japanese complete guides, including the Famitsu line Harvest Moon 64 volumes, and the better English Prima and BradyGames era books are priced as used books, not as collectibles, and they are the part of this market most likely to firm up, because print was finite and farming guides get used to death. A game and guide pairing also displays better than a game alone, which matters on a shelf that will be looked at more than it is played.
Save the American SNES Harvest Moon box and the American Harvest Moon 64 box for last, buy them slowly and in person where possible, and let everything else be bought with the confidence of a lane where supply is real. The core era rewards patience and punishes only the two trophy purchases. That is a kind budget, and it is why this section recommends the farm as a first serious retro shelf.