Browser based, text-based game prototype (including auction)

This is a brief for a browser-based prototype of a game, to be played by up to 2 to 100 players. I will provide a web server to host it on. I'm expecting something which looks very basic (no need for graphics, just text, tables, menus and links). I prefer to work with someone who has an interest in games, but being a game developer is not a requirement. It is a game about collecting items, and selling them to each other via an auction. It needs to have the functionality of a basic online auction. ELEMENTS OF THE GAME Item Database: There is a database provided by us (currently a Google spreadsheet) of unique items (each with ~10 attributes, e.g. Title, CollectionName, Description etc). The quantity of each unique item is predetermined (e.g. there may be only 1 of a very rare item, and 100 of a very common item), and this is a closed system. So if there is just 1 copy of item number 89, then only one of the players can own item 89 at a time. Player Database Up to 100 players, each have their own collection of up to 30 items. If they have a full collection and wish to buy a new item, they must first sell or discard an owned item to make room. Each player also has a coin balance (virtual currency). Auction Players can buy or sell their items on an auction, visible to all players. PAGES/AREAS WITHIN THE GAME (login/Registration: players must register a username, not for security but just so that they can see their account from multiple devices.) Auction: A basic auction in which players can browse the items currently listed (sortable by ‘ending soonest’ and ‘highest rarity’), and bid on those items. If a player is the highest bidder, that item becomes part of their collection. It should show the current highest bid and that bidder’s username. "My Collection": List of all the items which the player currently owns. Player’s collections are grouped into two categories (by the player), MyCollection (<21 items) and Spares (<11 items). It should include 'today's gift'. My Account: Should display player’s coin balance. Yesterday’s earnings. Leaderboard: List of the coin balance and ‘Yesterday’s earnings’ for all players. Daily activity Every day at midnight UTC, the game will: Add a coin revenue to every players’ coin balance. The formula for working this out is to be confirmed. Randomly allocate (‘gift’) an item from the database to each player. That's roughly it. I want a price for building this basic prototype, from which I would like to continue developing it in stages, agreeing a price each time for a new batch of changes. Thanks, JD.