If you wanna buy any asset you can't directly tell owner, you need searching him in real life. I suggest develop bid system.

- you finding needed asset;

- if this asset selling on marketplace, you can buy it or send the bid, if not, you can only send bid.

- you send bid volume and life time.

- press "Create".

- your ENJ blocking.

This method have some minuses:

- enj bloked until bid expiration;

- on each bid you spend gas.

Another way:

- you choose asset, push the button " I wanna it".

[- send the price.]

- each owner of this asset get notification on wallet.