2Vor 7 Monaten (Vor 7 Monaten)EXkuroganeEXkurogane
There are 4 types of graph curves for figure prices - the "u", the "n", and the upward or downward slope. Popularity and market price of a figure is highly dictated by the Japanese market, and then there are a host of factors to consider, and you will be able to predict it right for every 8 out of 10 figures.
My general rule of thumb is to preorder those predicted to fall in the n and upward curve category, and wait after release for those in the u or downward curve category.

The U is where the figure's price drops within a few months after release, but about 2 years later it starts rising. The figure is popular, but overproduced. But due to sustained popularity in the long term (because the anime series or manga is a long running one over many years with many seasons, and highly popular) stocks start to deplete over time, gets rare, and it starts rising, above the MSRP pricing, despite at one point it was a bargain item. Examples are Max factory's 1/6 Momo Belia Deviluke and Mea Kurosaki. Momo was about 9000yen+ on preorder, the lowest point was about 7000yen, but it rose to about 16,000yen by now. Mea had a similar pattern and i believe Sairenji haruna will follow a similar pattern over the next year or two.

The n curve is where the figure had a temporary high demand leading to increased value, but either loses popularity in the long term or a re-release led to fall of value. Figures made by companies who love to re-release their popular items are at risk of this pattern. This is one of the most common scenarios with most figures. Many of Kotobukiya's figures, almost all of Alter's Hyakka Ryouran Samurai Girls figures (including the exclusive ones) and K-On figures, and Good Smile Company's Saber Lily Distant Avalon are best examples - the latest victim being Good Smile's Saber Triumphant excalibur, already anticipated due to the popularity of Fate Grand Order.

The upward slope is where the figure will only keep increasing in value, never to drop again due to its rarity - yet because they are not mainstream or highly popular characters, they are almost certain to never get a re-release. Often figures of characters originating from games that are quite niche or only popular in Japan, as well as figures based off certain artworks. Examples: Good Smile's Beatless Lacia, Max Factory's Sallya, Good Smile Company's Insane Black Rock Shooter, Gift's Kashiwazaki Sena. I actually made a lot of money from this category, i bought Gift Sena for USD$90 in a local store stocks clearance sale and sold it for USD$299. I also sold my Good Smile's Saber Alter Vortigern for $230 because i anticipated its re-release (and value fall) which happened a year after i sold her. I realised she will end up in the N curve category instead of this one after fate Grand Order started to become popular.

The downward slope is where the figure drops in value (the degree of drop varies depending on character) and might remain in bargain bin level pricing because of poor quality, poor demand + overproduction, or figures of seasonal waifus where they are popular maybe for 6 months due to the anime, and then forgotten in the long run - well known victims are Hestia from Danmachi and Infinite Stratos' Charlotte Dunoa. One next possible victim is Shidare Hotaru from Dagashi Kashi. Anime was popular, but everyone forgets about it later on with no season 2 in sight, but some of her figures are not even released yet and people lose interest, cancel their orders, stocks accumulate and the price binning begins. Figures of mascot characters (Miku, Sonico) are also prone to this category unless it is unexpectedly popular and stock depletes.