The iShares S&P 500 ETF (ASX: IVV) has done fabulously well for investors in the past 12 months, up around 34%. The S&P/ASX 200 Index (ASX: XJO) has only risen by around 11% in the same time.

I would say it's unlikely that the IVV ETF will increase by another 34% over the next year.

After such a strong rise, it's important to ask the question of whether it's a good time to buy. I'm going to look at the pros and cons of potentially purchasing right now.

No business is a buy at any price, nor are the 500 largest US businesses a buy at any price.

Investing in assets is obviously better at lower prices rather than higher prices. We don't know when prices will move up or down, but volatility does regularly occur. Buying near all-time highs is not an ideal purchase price.

It's possible that a better price could be just around the corner, and we can earn a solid rate of interest income in the meantime.

Interest rates are very high compared to the last several years, which is meant to drag down on asset prices. Inflation is rising again in the US and this may mean that interest rates have to stay higher for longer than some investors are expecting. Today's valuations may have gotten ahead of themselves.

There is also the looming US election that could have an impact on US valuations, depending on what happens.

I think one of the most effective investment strategies for regular Aussies is to invest regularly in quality exchange-traded funds (ETFs). This can be called dollar cost averaging. Sometimes it means investing during a bear market at good prices and sometimes it means investing at higher prices.

Long-term growth over time has meant anyone who bought a decade ago, five years ago or a year ago has seen good capital growth. Capital growth is definitely not certain, particularly over shorter periods of time, but there are positive trends to help.

Businesses keep offering new and improved services, the population keeps rising, and the inflationary environment is helping (advantaged) companies increase prices. Bigger profits are one of the most helpful things to support higher share prices over time.

In a decade from now, I think the IVV ETF unit price could be substantially higher than where it is today.

If I were regularly investing in the iShares S&P 500 ETF, I'd be willing to invest right now and hold for the long term.

However, if I had a one-off $5,000 to invest, I'd be willing to wait for a lower price sometime this year. I still think there are a number of good value ASX shares closer to home.