Last week, I banged the drum on lowering costs for investors – in particular, by focusing on exchange traded funds (ETFs) purchased through regular investment plans run by online stockbrokers.

This week, it’s the turn of another rival to the expensive wrap platform-based unit trust sector: investment trusts.

I invest in a bunch of them through regular monthly savings plans – including the Aberdeen Asian funds, RIT Capital Partners, Blue Planet’s global banking fund, TR Property, and Advance Frontier markets.

I’m a big fan of investment trusts – they are aimed at adventurous, sophisticated investors as well as institutions. I also like their ability to gear up if returns are looking strong (using sensible levels of debt) and I’m a big fan of niche funds with specific mandates, such as frontier markets or global banks.

So, if I want to buy some access to actively-managed funds that provide alpha, my default position is an investment trust – especially when the average total expense ratio (TER) of an investment trust is 1.39 per cent, and many charge closer to 1.1 per cent. That figure is much higher than the equivalent for ETFs – you’re paying for those active fund managers – but it’s still a lot lower than the average unit trust bought through a wrap platform where trail commission to your financial adviser raises the average TER to 1.65 per cent.

Crucially, many investment trusts operate monthly savings plans that let you plough between £30 and £250 a month into a their funds. No-one yet provides a platform that lets you invest across providers – although I think that would be a terrific idea (hint)!

After all, the costs on these schemes are tiny. Typically, there’s no purchase fee nor annual fee. The only charge you’d face is if you wanted to sell or transfer out, at which point you’d probably trigger a one-off fee of £20-£40 or between 0.5 per cent and 1.2 per cent of investment value in charges.

So no upfront purchase fee, no dealing charges to buy, lower TERs – you do the maths and tell me that this isn’t a better idea than your average unit trust on a wrap platform!

The investment trust sector is also a great place to go hunting for slightly off-the-wall investments – and I have two cracking ideas for you this week.

The first idea is one I’ve already taken advantage of, via my self-invested personal pension (Sipp): new subscription shares in Ecofin Water and Power, the specialist utilities fund.

These subscription shares are like warrants in that they allow investors to buy ordinary shares at a predetermined price in the future. But, unlike warrants, you can hold these shares in an individual savings account (Isa). According to the fund managers, the subscription shares have a life of approximately three years, expiring on May 31 2012. Shareholders will be able to exercise their subscription shares twice a year, on May 31 and on November 30. The exercise prices are as follows:

● on or prior to May 31 2010, at an exercise price of 168p per share (compared with the existing net asset value of 170p)

● after May 31 2010 and up to May 31 2011, at an exercise price of 172p per share (representing a premium of 3 per cent to the existing NAV of 170p)

● after May 31 2011, at an exercise price of 183p per share (representing a premium of 10 per cent to the existing NAV).

I’ve long held Ecofin’s shares and they’ve done me proud. I’m a fan of the managers’ active approach – they’re not afraid to use a private equity style approach if they think it will release more value. Add in the fairly strong cashflow profile of the underlying investments and the normally elevated dividends, and you have an attractive investment. Clearly, these subscription shares are not a good buy if we’re in a continued bear market but, if you believe the markets will start to move up, I’d wager these shares will shoot up.

And Ecofin’s new subscription shares are not alone – in my online diary next week, I’ll look at a bunch of other warrants that are a great play on emerging markets.

My second idea is a fairly mainstream investment trust called Investors Capital. This came across my radar after a note from its manager in Investment Week, the specialist trade magazine – Mike Woodward at F&C pointed out that the B shares in this hybrid equity income/bond fund pay out their dividend not as a cheque but via something called a small capital receipt.

The net effect is that the 8.2 per cent yield avoids income tax, which is hugely important if you’re a higher rate taxpayer who wants to pay the capital gains tax rate of 18 per cent instead.

There’s also the bonus that this “high income” fund is a pretty impressive performer – it was down 24 per cent in 2008 compared with the average fall of 44 per cent for other high-income funds – and it boasts a nice mixed bag of corporate bonds and high-yielding blue chips.

I’m not necessarily a big fan of its UK equity focus, but I like its ability to move between equities and bonds/gilts – and the features of the B-class shares seem especially appealing.