Simple google searches do this. Look at items with their high alch price then go to GE and see what their buy price is.
Items you can try: yew longbows, dragonhide bodies, staves, rune armour, etc.
Rather than high-alching, I would train magic via string jewelry or plank make if those options are available to you. If not, battlestaves or various rune items have always been good items to alch. In fact, I remember some god items like the armadyl plateskirt had a price of ~36k while they alched for ~39k, but I'm not sure if the prices are the same and the supply is obviously very low. It's still something that might be worth looking into though.
Magic longbows/yew longbows if you alch. I would recommend stun alching or stringing jewelry for faster experience though.
My suggestion ; metal armor/weapons. This includes anything from iron-rune. Look up prices/alch values as a lot of these metal armors are very undervalued in the ge/trade values. Stay away from the traditional ''yew/maple/magic bows'' and try find something unique that works. I found that on some days you can alch mithril armor such as med helms for profit. This isn't guaranteed profit but there are always items that yield profit.

