It depends on your items, how many you have, and a few other things as to whether a store would be more beneficial or not, there's lots of category specific info, as well, which can make things a bit confusing at times.
Fee-wise, since your items are in the toys category, the fee will drop from 9.9% to 8% with a basic store. The 200 free listings that come with a basic store are for fixed price (buy it now) format, in any category, and auctions only within the collectible categories (so doesn't inlcude toys - the FVF in collectible categories only drops to 9.5% with a store, as well). After the 200 free listings are used, each Buy It Now costs 50c, and each auction will cost $1.50, except if in a collectible category, then it will cost $1 (an auction in any other category will cost $1.50 with a store even if you have all your free listings available).
In general, the primary advantages of a store is that your items can be listed for up to 30 days at a time, or as 'good til cancelled', meaning the listing lasts until sold out or manually ended (they still have a 30 day cycle, so every 30 days the listing ticks over and either uses one of the free listings that comes with a store, or it is charged a new listing fee if you've gone over). These kinds of listings are simple to maintain as long as you keep an eye on stock levels (if you have multiples) and are good for building sales history / best match rankings. Store categories can make it easier to organise your item listings by type, or whatever sub-categories would suit your items, selling manager pro is free if you opt to subscribe, and you can access promotional and discounting tools.
Disadvantages I suppose would mostly be related to turnover. Store / Buy It Now listings can move slower than regular auctions because they usually only end when someone buys, so no sense of 'missed opportunity' by a clock ticking down, but IMO that's becoming less and less an issue, especially if an item is readily available most of the time.
